Update version

.github/ISSUE_TEMPLATE/bug-report.yml

@@ -1,42 +1,75 @@
-name: 🐞 Bug report
+name: 🐛 Bug report
 description: Report broken functionality.
 labels: [bug]
 
 body:
-- type: markdown
-  attributes:
-    value: |
-      🧐 **Guidelines:**
+  - type: markdown
+    attributes:
+      value: |
+        - Avoid generic or vague titles such as "Something's not working" or "A couple of problems" — be as descriptive as possible.
+        - Keep your issue focused on one single problem. If you have multiple bug reports, please create a separate issue for each of them.
+        - Issues should represent **complete and actionable** work items. If you are unsure about something or have a question, please start a [discussion](https://github.com/Tyrrrz/CliFx/discussions/new) instead.
+        - Remember that **CliFx** is an open-source project funded by the community. If you find it useful, **please consider [donating](https://tyrrrz.me/donate) to support its development**.
 
-      - Search through [existing issues](https://github.com/Tyrrrz/CliFx/issues?q=is%3Aissue) first to ensure that this bug has not been reported before.
-      - Write a descriptive title for your issue. Avoid generic or vague titles such as "Something's not working" or "A couple of problems".
-      - Keep your issue focused on one single problem. If you have multiple bug reports, please create separate issues for each of them.
-      - Provide as much context as possible in the details section. Include screenshots, screen recordings, links, references, or anything else you may consider relevant.
-      - If you want to ask a question instead of reporting a bug, please use [discussions](https://github.com/Tyrrrz/CliFx/discussions/new) instead.
+        ___
 
-- type: input
-  attributes:
-    label: Version
-    description: Which version of CliFx does this bug affect?
-    placeholder: ver X.Y.Z
-  validations:
-    required: true
+  - type: input
+    attributes:
+      label: Version
+      description: Which version of the package does this bug affect? Make sure you're not using an outdated version.
+      placeholder: v1.0.0
+    validations:
+      required: true
 
-- type: textarea
-  attributes:
-    label: Details
-    description: Clear and thorough explanation of the bug.
-    placeholder: I was doing X expecting Y to happen, but Z happened instead.
-  validations:
-    required: true
+  - type: input
+    attributes:
+      label: Platform
+      description: Which platform do you experience this bug on?
+      placeholder: .NET 7.0 / Windows 11
+    validations:
+      required: true
 
-- type: textarea
-  attributes:
-    label: Steps to reproduce
-    description: Minimum steps required to reproduce the bug.
-    placeholder: |
-      - Step 1
-      - Step 2
-      - Step 3
-  validations:
-    required: true
+  - type: textarea
+    attributes:
+      label: Steps to reproduce
+      description: >
+        Minimum steps required to reproduce the bug, including prerequisites, code snippets, or other relevant items.
+        The information provided in this field must be readily actionable, meaning that anyone should be able to reproduce the bug by following these steps.
+        If the reproduction steps are too complex to fit in this field, please provide a link to a repository instead.
+      placeholder: |
+        - Step 1
+        - Step 2
+        - Step 3
+    validations:
+      required: true
+
+  - type: textarea
+    attributes:
+      label: Details
+      description: Clear and thorough explanation of the bug, including any additional information you may find relevant.
+      placeholder: |
+        - Expected behavior: ...
+        - Actual behavior: ...
+    validations:
+      required: true
+
+  - type: checkboxes
+    attributes:
+      label: Checklist
+      description: Quick list of checks to ensure that everything is in order.
+      options:
+        - label: I have looked through existing issues to make sure that this bug has not been reported before
+          required: true
+        - label: I have provided a descriptive title for this issue
+          required: true
+        - label: I have made sure that that this bug is reproducible on the latest version of the package
+          required: true
+        - label: I have provided all the information needed to reproduce this bug as efficiently as possible
+          required: true
+        - label: I have sponsored this project
+          required: false
+
+  - type: markdown
+    attributes:
+      value: |
+        If you are struggling to provide actionable reproduction steps, or if something else is preventing you from creating a complete bug report, please start a [discussion](https://github.com/Tyrrrz/CliFx/discussions/new) instead.

.github/ISSUE_TEMPLATE/config.yml

@@ -3,9 +3,9 @@ contact_links:
   - name: ⚠ Feature request
     url: https://github.com/Tyrrrz/.github/blob/master/docs/project-status.md
     about: Sorry, but this project is in maintenance mode and no longer accepts new feature requests.
+  - name: 🗨 Discussions
+    url: https://github.com/Tyrrrz/CliFx/discussions/new
+    about: Ask and answer questions.
   - name: 💬 Discord server
     url: https://discord.gg/2SUWKFnHSm
     about: Chat with the project community.
-  - name: 🗨 Discussions
-    url: https://github.com/Tyrrrz/CliFx/discussions/new
-    about: Ask and answer questions.

.github/workflows/main.yml

@@ -1,13 +1,29 @@
 name: main
 
-on: [push, pull_request]
+on:
+  workflow_dispatch:
+    inputs:
+      package-version:
+        type: string
+        description: Package version
+        required: false
+      deploy:
+        type: boolean
+        description: Deploy package
+        required: false
+        default: false
+  push:
+  pull_request:
 
 jobs:
   main:
     uses: Tyrrrz/.github/.github/workflows/nuget.yml@master
     with:
-      dotnet-version: 7.0.x
+      dotnet-version: 8.0.x
+      package-version: ${{ inputs.package-version }}
+      # Deploy only on tags by default, unless deploy is explicitly requested
+      deploy-on-tags-only: ${{ !(github.event_name == 'workflow_dispatch' && inputs.deploy) }}
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
       NUGET_TOKEN: ${{ secrets.NUGET_TOKEN }}
-      DISCORD_WEBHOOK: ${{ secrets.DISCORD_WEBHOOK }}
+      DISCORD_WEBHOOK: ${{ secrets.DISCORD_WEBHOOK }}

.gitignore

@@ -1,21 +1,12 @@
 # User-specific files
+.vs/
+.idea/
 *.suo
 *.user
-*.userosscache
-*.sln.docstates
-.idea/
 
 # Build results
-[Dd]ebug/
-[Dd]ebugPublic/
-[Rr]elease/
-[Rr]eleases/
-[Xx]64/
-[Xx]86/
-[Bb]uild/
-bld/
-[Bb]in/
-[Oo]bj/
+bin/
+obj/
 
-# Coverage
-*.opencover.xml
+# Test results
+TestResults/

Changelog.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## v2.3.5 (16-Nov-2023)
+
+- Fixed an issue where calling `CliApplication.RunAsync(IReadOnlyList<string>)` could fail in very specific scenarios on Windows, if there were two global environment variables with the same name but different casing. (Thanks [@alirezanet](https://github.com/alirezanet))
+
+## v2.3.4 (18-May-2023)
+
+- Added an overload of `CliApplicationBuilder.UseTypeActivator(...)` that accepts a `Func<IReadOnlyList<Type>, IServiceProvider>` delegate. The first parameter in the delegate is the list of all command types registered in the application. You can use this overload to more easily add the commands to a DI container. See the readme for an [updated example](https://github.com/Tyrrrz/CliFx/tree/2.3.4#type-activation).
+
 ## v2.3.3 (28-Apr-2023)
 
 - Fixed an issue where the analyzers failed to load in some projects, due to targeting a Roslyn version that was too high.

CliFx.Analyzers.Tests/CliFx.Analyzers.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
@@ -9,14 +9,15 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.1" />
-    <PackageReference Include="GitHubActionsTestLogger" Version="2.0.2" PrivateAssets="all" />
-    <PackageReference Include="FluentAssertions" Version="6.11.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
-    <PackageReference Include="xunit" Version="2.4.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" PrivateAssets="all" />
-    <PackageReference Include="coverlet.collector" Version="3.2.0" PrivateAssets="all" />
+    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.5" />
+    <PackageReference Include="coverlet.collector" Version="6.0.0" PrivateAssets="all" />
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
+    <PackageReference Include="GitHubActionsTestLogger" Version="2.3.3" PrivateAssets="all" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.7.0" />
+    <PackageReference Include="xunit" Version="2.6.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

CliFx.Analyzers.Tests/CommandMustBeAnnotatedAnalyzerSpecs.cs

@@ -12,9 +12,8 @@ public class CommandMustBeAnnotatedAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_command_is_not_annotated_with_the_command_attribute()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
@@ -29,9 +28,8 @@ public class CommandMustBeAnnotatedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_command_is_annotated_with_the_command_attribute()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public abstract class MyCommand : ICommand
             {
@@ -47,9 +45,8 @@ public class CommandMustBeAnnotatedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_command_is_implemented_as_an_abstract_class()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public abstract class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
@@ -64,16 +61,15 @@ public class CommandMustBeAnnotatedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_class_that_is_not_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class Foo
             {
-                public int Bar { get; set; } = 5;
+                public int Bar { get; init; } = 5;
             }
             """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/CommandMustImplementInterfaceAnalyzerSpecs.cs

@@ -6,15 +6,15 @@ namespace CliFx.Analyzers.Tests;
 
 public class CommandMustImplementInterfaceAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new CommandMustImplementInterfaceAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new CommandMustImplementInterfaceAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_command_does_not_implement_ICommand_interface()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand
             {
@@ -30,9 +30,8 @@ public class CommandMustImplementInterfaceAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_command_implements_ICommand_interface()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -48,16 +47,15 @@ public class CommandMustImplementInterfaceAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_class_that_is_not_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class Foo
             {
-                public int Bar { get; set; } = 5;
+                public int Bar { get; init; } = 5;
             }
             """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/GeneralSpecs.cs

@@ -16,7 +16,7 @@ public class GeneralSpecs
             .Assembly
             .GetTypes()
             .Where(t => !t.IsAbstract && t.IsAssignableTo(typeof(DiagnosticAnalyzer)))
-            .Select(t => (DiagnosticAnalyzer) Activator.CreateInstance(t)!)
+            .Select(t => (DiagnosticAnalyzer)Activator.CreateInstance(t)!)
             .ToArray();
 
         // Act
@@ -27,4 +27,4 @@ public class GeneralSpecs
         // Assert
         diagnosticIds.Should().OnlyHaveUniqueItems();
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustBeInsideCommandAnalyzerSpecs.cs

@@ -12,13 +12,12 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_is_inside_a_class_that_is_not_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyClass
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             }
             """;
 
@@ -30,14 +29,13 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_is_inside_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -51,13 +49,12 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_is_inside_an_abstract_class()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public abstract class MyCommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             }
             """;
 
@@ -69,13 +66,12 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -84,4 +80,4 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs.cs

@@ -6,20 +6,20 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustBeRequiredIfPropertyRequiredAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustBeRequiredIfPropertyRequiredAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_non_required_option_is_bound_to_a_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f', IsRequired = false)]
-                public required string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -33,14 +33,13 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_required_option_is_bound_to_a_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                [CommandOption('f', IsRequired = true)]
-                public required string Foo { get; set; }
+                [CommandOption('f')]
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -54,14 +53,13 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_required_option_is_bound_to_a_non_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f', IsRequired = false)]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -75,14 +73,13 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_required_option_is_bound_to_a_non_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                [CommandOption('f', IsRequired = true)]
-                public string Foo { get; set; }
+                [CommandOption('f')]
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -96,13 +93,12 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public required string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -111,4 +107,4 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveNameOrShortNameAnalyzerSpecs.cs

@@ -6,20 +6,20 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustHaveNameOrShortNameAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustHaveNameOrShortNameAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustHaveNameOrShortNameAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_an_option_does_not_have_a_name_or_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption(null)]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -33,14 +33,13 @@ public class OptionMustHaveNameOrShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -54,14 +53,13 @@ public class OptionMustHaveNameOrShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -75,13 +73,12 @@ public class OptionMustHaveNameOrShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -90,4 +87,4 @@ public class OptionMustHaveNameOrShortNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveUniqueNameAnalyzerSpecs.cs

@@ -12,17 +12,16 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_has_the_same_name_as_another_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 [CommandOption("foo")]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -36,17 +35,16 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_unique_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 [CommandOption("bar")]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -60,14 +58,13 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_a_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -81,13 +78,12 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -96,4 +92,4 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveUniqueShortNameAnalyzerSpecs.cs

@@ -6,23 +6,23 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustHaveUniqueShortNameAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustHaveUniqueShortNameAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustHaveUniqueShortNameAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_an_option_has_the_same_short_name_as_another_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 [CommandOption('f')]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -36,17 +36,16 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_unique_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 [CommandOption('b')]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -60,17 +59,16 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_short_name_which_is_unique_only_in_casing()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 [CommandOption('F')]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -84,14 +82,13 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_a_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -105,13 +102,12 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -120,4 +116,4 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveValidConverterAnalyzerSpecs.cs

@@ -6,26 +6,26 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustHaveValidConverterAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustHaveValidConverterAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustHaveValidConverterAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_an_option_has_a_converter_that_does_not_derive_from_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter
             {
-                public string Convert(string rawValue) => rawValue;
+                public string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -38,20 +38,19 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_has_a_converter_that_does_not_derive_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<int>
             {
-                public override int Convert(string rawValue) => 42;
+                public override int Convert(string? rawValue) => 42;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -64,20 +63,19 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<string>
             {
-                public override string Convert(string rawValue) => rawValue;
+                public override string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -90,20 +88,19 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_nullable_option_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<int>
             {
-                public override int Convert(string rawValue) => 42;
+                public override int Convert(string? rawValue) => 42;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public int? Foo { get; set; }
-            
+                public int? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -116,20 +113,19 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_scalar_option_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<string>
             {
-                public override string Convert(string rawValue) => rawValue;
+                public override string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public IReadOnlyList<string> Foo { get; set; }
-            
+                public IReadOnlyList<string>? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -142,15 +138,14 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_a_converter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -163,14 +158,13 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -178,4 +172,4 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveValidNameAnalyzerSpecs.cs

@@ -12,14 +12,13 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_has_a_name_which_is_too_short()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("f")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -33,14 +32,13 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_has_a_name_that_starts_with_a_non_letter_character()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("1foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -54,14 +52,13 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_valid_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -75,14 +72,13 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_a_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -96,13 +92,12 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -111,4 +106,4 @@ public class OptionMustHaveValidNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveValidShortNameAnalyzerSpecs.cs

@@ -6,20 +6,20 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustHaveValidShortNameAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustHaveValidShortNameAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustHaveValidShortNameAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_an_option_has_a_short_name_which_is_not_a_letter_character()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('1')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -33,14 +33,13 @@ public class OptionMustHaveValidShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_a_valid_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -54,14 +53,13 @@ public class OptionMustHaveValidShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_a_short_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -75,13 +73,12 @@ public class OptionMustHaveValidShortNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -90,4 +87,4 @@ public class OptionMustHaveValidShortNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/OptionMustHaveValidValidatorsAnalyzerSpecs.cs

@@ -6,15 +6,15 @@ namespace CliFx.Analyzers.Tests;
 
 public class OptionMustHaveValidValidatorsAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new OptionMustHaveValidValidatorsAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new OptionMustHaveValidValidatorsAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_an_option_has_a_validator_that_does_not_derive_from_BindingValidator()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator
             {
                 public void Validate(string value) {}
@@ -24,7 +24,7 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -38,9 +38,8 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_reports_an_error_if_an_option_has_a_validator_that_does_not_derive_from_a_compatible_BindingValidator()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator : BindingValidator<int>
             {
                 public override BindingValidationError Validate(int value) => Ok();
@@ -50,7 +49,7 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -64,9 +63,8 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_has_validators_that_all_derive_from_compatible_BindingValidators()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator : BindingValidator<string>
             {
                 public override BindingValidationError Validate(string value) => Ok();
@@ -76,7 +74,7 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -90,14 +88,13 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_an_option_does_not_have_validators()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -111,13 +108,12 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -126,4 +122,4 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeInsideCommandAnalyzerSpecs.cs

@@ -6,19 +6,19 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeInsideCommandAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeInsideCommandAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeInsideCommandAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_parameter_is_inside_a_class_that_is_not_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyClass
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
             }
             """;
 
@@ -30,15 +30,14 @@ public class ParameterMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_is_inside_a_command()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -51,13 +50,12 @@ public class ParameterMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_is_inside_an_abstract_class()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public abstract class MyCommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
             }
             """;
 
@@ -69,14 +67,13 @@ public class ParameterMustBeInsideCommandAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -84,4 +81,4 @@ public class ParameterMustBeInsideCommandAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeLastIfNonRequiredAnalyzerSpecs.cs

@@ -6,24 +6,24 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeLastIfNonRequiredAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeLastIfNonRequiredAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_non_required_parameter_is_not_the_last_in_order()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, IsRequired = false)]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +36,17 @@ public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_required_parameter_is_the_last_in_order()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1, IsRequired = false)]
-                public string Bar { get; set; }
-            
+                public string? Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,18 +59,17 @@ public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_no_non_required_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
-                [CommandParameter(1, IsRequired = true)]
-                public string Bar { get; set; }
-            
+                public required string Foo { get; init; }
+
+                [CommandParameter(1)]
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -84,14 +82,13 @@ public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -99,4 +96,4 @@ public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeLastIfNonScalarAnalyzerSpecs.cs

@@ -6,24 +6,24 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeLastIfNonScalarAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeLastIfNonScalarAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_non_scalar_parameter_is_not_the_last_in_order()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string[] Foo { get; set; }
-            
+                public required string[] Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +36,17 @@ public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_scalar_parameter_is_the_last_in_order()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string[] Bar { get; set; }
-            
+                public required string[] Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,18 +59,17 @@ public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_no_non_scalar_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -84,14 +82,13 @@ public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -99,4 +96,4 @@ public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs.cs

@@ -6,20 +6,20 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeRequiredIfPropertyRequiredAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeRequiredIfPropertyRequiredAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_non_required_parameter_is_bound_to_a_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, IsRequired = false)]
-                public required string Foo { get; set; }
+                public required string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -33,14 +33,13 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_required_parameter_is_bound_to_a_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                [CommandParameter(0, IsRequired = true)]
-                public required string Foo { get; set; }
+                [CommandParameter(0)]
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -54,14 +53,13 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_required_parameter_is_bound_to_a_non_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, IsRequired = false)]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -75,14 +73,13 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_required_parameter_is_bound_to_a_non_required_property()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                [CommandParameter(0, IsRequired = true)]
-                public string Foo { get; set; }
+                [CommandParameter(0)]
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -96,13 +93,12 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public required string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -111,4 +107,4 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeSingleIfNonRequiredAnalyzerSpecs.cs

@@ -6,24 +6,24 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeSingleIfNonRequiredAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeSingleIfNonRequiredAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_more_than_one_non_required_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, IsRequired = false)]
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 [CommandParameter(1, IsRequired = false)]
-                public string Bar { get; set; }
-            
+                public string? Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +36,17 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_only_one_non_required_parameter_is_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1, IsRequired = false)]
-                public string Bar { get; set; }
-            
+                public string? Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,18 +59,17 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_no_non_required_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
-                [CommandParameter(1, IsRequired = true)]
-                public string Bar { get; set; }
-            
+                public required string Foo { get; init; }
+
+                [CommandParameter(1)]
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -84,14 +82,13 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -99,4 +96,4 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustBeSingleIfNonScalarAnalyzerSpecs.cs

@@ -6,24 +6,24 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustBeSingleIfNonScalarAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustBeSingleIfNonScalarAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_more_than_one_non_scalar_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string[] Foo { get; set; }
-            
+                public required string[] Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string[] Bar { get; set; }
-            
+                public required string[] Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +36,17 @@ public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_only_one_non_scalar_parameter_is_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string[] Bar { get; set; }
-            
+                public required string[] Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,18 +59,17 @@ public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_no_non_scalar_parameters_are_defined()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -84,14 +82,13 @@ public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -99,4 +96,4 @@ public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustHaveUniqueNameAnalyzerSpecs.cs

@@ -12,18 +12,17 @@ public class ParameterMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_parameter_has_the_same_name_as_another_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Name = "foo")]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1, Name = "foo")]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +35,17 @@ public class ParameterMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_has_unique_name()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Name = "foo")]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1, Name = "bar")]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,14 +58,13 @@ public class ParameterMustHaveUniqueNameAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -75,4 +72,4 @@ public class ParameterMustHaveUniqueNameAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustHaveUniqueOrderAnalyzerSpecs.cs

@@ -6,24 +6,24 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustHaveUniqueOrderAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustHaveUniqueOrderAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustHaveUniqueOrderAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_parameter_has_the_same_order_as_another_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(0)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -36,18 +36,17 @@ public class ParameterMustHaveUniqueOrderAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_has_unique_order()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 [CommandParameter(1)]
-                public string Bar { get; set; }
-            
+                public required string Bar { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -60,14 +59,13 @@ public class ParameterMustHaveUniqueOrderAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -75,4 +73,4 @@ public class ParameterMustHaveUniqueOrderAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustHaveValidConverterAnalyzerSpecs.cs

@@ -6,26 +6,26 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustHaveValidConverterAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustHaveValidConverterAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustHaveValidConverterAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_parameter_has_a_converter_that_does_not_derive_from_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter
             {
-                public string Convert(string rawValue) => rawValue;
+                public string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -38,25 +38,23 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_parameter_has_a_converter_that_does_not_derive_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<int>
             {
-                public override int Convert(string rawValue) => 42;
+                public override int Convert(string? rawValue) => 42;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
 
-
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
     }
@@ -65,20 +63,19 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<string>
             {
-                public override string Convert(string rawValue) => rawValue;
+                public override string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Converter = typeof(MyConverter))]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -91,20 +88,19 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_nullable_parameter_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<int>
             {
-                public override int Convert(string rawValue) => 42;
+                public override int Convert(string? rawValue) => 42;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandOption("foo", Converter = typeof(MyConverter))]
-                public int? Foo { get; set; }
-            
+                public int? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -117,20 +113,19 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_non_scalar_parameter_has_a_converter_that_derives_from_a_compatible_BindingConverter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyConverter : BindingConverter<string>
             {
-                public override string Convert(string rawValue) => rawValue;
+                public override string Convert(string? rawValue) => rawValue;
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Converter = typeof(MyConverter))]
-                public IReadOnlyList<string> Foo { get; set; }
-            
+                public required IReadOnlyList<string> Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -143,15 +138,14 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_does_not_have_a_converter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -164,14 +158,13 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -179,4 +172,4 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/ParameterMustHaveValidValidatorsAnalyzerSpecs.cs

@@ -6,26 +6,26 @@ namespace CliFx.Analyzers.Tests;
 
 public class ParameterMustHaveValidValidatorsAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new ParameterMustHaveValidValidatorsAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new ParameterMustHaveValidValidatorsAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_a_parameter_has_a_validator_that_does_not_derive_from_BindingValidator()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator
             {
                 public void Validate(string value) {}
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -38,20 +38,19 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_parameter_has_a_validator_that_does_not_derive_from_a_compatible_BindingValidator()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator : BindingValidator<int>
             {
                 public override BindingValidationError Validate(int value) => Ok();
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -64,20 +63,19 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_has_validators_that_all_derive_from_compatible_BindingValidators()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             public class MyValidator : BindingValidator<string>
             {
                 public override BindingValidationError Validate(string value) => Ok();
             }
-            
+
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0, Validators = new[] {typeof(MyValidator)})]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -90,15 +88,14 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_parameter_does_not_have_validators()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
-            
+                public required string Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -111,14 +108,13 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
-                public string Foo { get; set; }
-            
+                public string? Foo { get; init; }
+
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
             """;
@@ -126,4 +122,4 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/SystemConsoleShouldBeAvoidedAnalyzerSpecs.cs

@@ -6,15 +6,15 @@ namespace CliFx.Analyzers.Tests;
 
 public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
 {
-    private static DiagnosticAnalyzer Analyzer { get; } = new SystemConsoleShouldBeAvoidedAnalyzer();
+    private static DiagnosticAnalyzer Analyzer { get; } =
+        new SystemConsoleShouldBeAvoidedAnalyzer();
 
     [Fact]
     public void Analyzer_reports_an_error_if_a_command_calls_a_method_on_SystemConsole()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -34,9 +34,8 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_command_accesses_a_property_on_SystemConsole()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -56,9 +55,8 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     public void Analyzer_reports_an_error_if_a_command_calls_a_method_on_a_property_of_SystemConsole()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -78,9 +76,8 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_command_interacts_with_the_console_through_IConsole()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -100,9 +97,8 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_IConsole_is_not_available_in_the_current_method()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -120,9 +116,8 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     public void Analyzer_does_not_report_an_error_if_a_command_does_not_access_SystemConsole()
     {
         // Arrange
-        // language=cs
-        const string code =
-            """
+        // lang=csharp
+        const string code = """
             [Command]
             public class MyCommand : ICommand
             {
@@ -136,4 +131,4 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
     }
-}
+}

CliFx.Analyzers.Tests/Utils/AnalyzerAssertions.cs

@@ -18,9 +18,7 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
     protected override string Identifier { get; } = "analyzer";
 
     public AnalyzerAssertions(DiagnosticAnalyzer analyzer)
-        : base(analyzer)
-    {
-    }
+        : base(analyzer) { }
 
     private Compilation Compile(string sourceCode)
     {
@@ -43,10 +41,10 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
 
         // Append default imports to the source code
         var sourceCodeWithUsings =
-            string.Join(Environment.NewLine, defaultSystemNamespaces.Select(n => $"using {n};")) +
-            string.Join(Environment.NewLine, defaultCliFxNamespaces.Select(n => $"using {n};")) +
-            Environment.NewLine +
-            sourceCode;
+            string.Join(Environment.NewLine, defaultSystemNamespaces.Select(n => $"using {n};"))
+            + string.Join(Environment.NewLine, defaultCliFxNamespaces.Select(n => $"using {n};"))
+            + Environment.NewLine
+            + sourceCode;
 
         // Parse the source code
         var ast = SyntaxFactory.ParseSyntaxTree(
@@ -58,7 +56,9 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
         var compilation = CSharpCompilation.Create(
             "CliFxTests_DynamicAssembly_" + Guid.NewGuid(),
             new[] { ast },
-            Net70.References.All
+            Net70
+                .References
+                .All
                 .Append(MetadataReference.CreateFromFile(typeof(ICommand).Assembly.Location)),
             // DLL to avoid having to define the Main() method
             new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
@@ -103,44 +103,47 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
         var producedDiagnosticIds = producedDiagnostics.Select(d => d.Id).Distinct().ToArray();
 
         var isSuccessfulAssertion =
-            expectedDiagnosticIds.Intersect(producedDiagnosticIds).Count() ==
-            expectedDiagnosticIds.Length;
+            expectedDiagnosticIds.Intersect(producedDiagnosticIds).Count()
+            == expectedDiagnosticIds.Length;
 
-        Execute.Assertion.ForCondition(isSuccessfulAssertion).FailWith(() =>
-        {
-            var buffer = new StringBuilder();
-
-            buffer.AppendLine("Expected and produced diagnostics do not match.");
-            buffer.AppendLine();
-
-            buffer.AppendLine("Expected diagnostics:");
-
-            foreach (var expectedDiagnostic in expectedDiagnostics)
+        Execute
+            .Assertion
+            .ForCondition(isSuccessfulAssertion)
+            .FailWith(() =>
             {
-                buffer.Append("  - ");
-                buffer.Append(expectedDiagnostic.Id);
+                var buffer = new StringBuilder();
+
+                buffer.AppendLine("Expected and produced diagnostics do not match.");
                 buffer.AppendLine();
-            }
 
-            buffer.AppendLine();
+                buffer.AppendLine("Expected diagnostics:");
 
-            buffer.AppendLine("Produced diagnostics:");
-
-            if (producedDiagnostics.Any())
-            {
-                foreach (var producedDiagnostic in producedDiagnostics)
+                foreach (var expectedDiagnostic in expectedDiagnostics)
                 {
                     buffer.Append("  - ");
-                    buffer.Append(producedDiagnostic);
+                    buffer.Append(expectedDiagnostic.Id);
+                    buffer.AppendLine();
                 }
-            }
-            else
-            {
-                buffer.AppendLine("  < none >");
-            }
 
-            return new FailReason(buffer.ToString());
-        });
+                buffer.AppendLine();
+
+                buffer.AppendLine("Produced diagnostics:");
+
+                if (producedDiagnostics.Any())
+                {
+                    foreach (var producedDiagnostic in producedDiagnostics)
+                    {
+                        buffer.Append("  - ");
+                        buffer.Append(producedDiagnostic);
+                    }
+                }
+                else
+                {
+                    buffer.AppendLine("  < none >");
+                }
+
+                return new FailReason(buffer.ToString());
+            });
     }
 
     public void NotProduceDiagnostics(string sourceCode)
@@ -148,27 +151,30 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
         var producedDiagnostics = GetProducedDiagnostics(sourceCode);
         var isSuccessfulAssertion = !producedDiagnostics.Any();
 
-        Execute.Assertion.ForCondition(isSuccessfulAssertion).FailWith(() =>
-        {
-            var buffer = new StringBuilder();
-
-            buffer.AppendLine("Expected no produced diagnostics.");
-            buffer.AppendLine();
-
-            buffer.AppendLine("Produced diagnostics:");
-
-            foreach (var producedDiagnostic in producedDiagnostics)
+        Execute
+            .Assertion
+            .ForCondition(isSuccessfulAssertion)
+            .FailWith(() =>
             {
-                buffer.Append("  - ");
-                buffer.Append(producedDiagnostic);
-            }
+                var buffer = new StringBuilder();
 
-            return new FailReason(buffer.ToString());
-        });
+                buffer.AppendLine("Expected no produced diagnostics.");
+                buffer.AppendLine();
+
+                buffer.AppendLine("Produced diagnostics:");
+
+                foreach (var producedDiagnostic in producedDiagnostics)
+                {
+                    buffer.Append("  - ");
+                    buffer.Append(producedDiagnostic);
+                }
+
+                return new FailReason(buffer.ToString());
+            });
     }
 }
 
 internal static class AnalyzerAssertionsExtensions
 {
     public static AnalyzerAssertions Should(this DiagnosticAnalyzer analyzer) => new(analyzer);
-}
+}

CliFx.Analyzers/AnalyzerBase.cs

@@ -14,7 +14,8 @@ public abstract class AnalyzerBase : DiagnosticAnalyzer
     protected AnalyzerBase(
         string diagnosticTitle,
         string diagnosticMessage,
-        DiagnosticSeverity diagnosticSeverity = DiagnosticSeverity.Error)
+        DiagnosticSeverity diagnosticSeverity = DiagnosticSeverity.Error
+    )
     {
         SupportedDiagnostic = new DiagnosticDescriptor(
             "CliFx_" + GetType().Name.TrimEnd("Analyzer"),
@@ -36,4 +37,4 @@ public abstract class AnalyzerBase : DiagnosticAnalyzer
         context.EnableConcurrentExecution();
         context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
     }
-}
+}

CliFx.Analyzers/CliFx.Analyzers.csproj

@@ -17,10 +17,11 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
     <!-- Make sure to target the lowest possible version of the compiler for wider support -->
     <PackageReference Include="Microsoft.CodeAnalysis" Version="3.0.0" PrivateAssets="all" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.0.0" PrivateAssets="all" />
-    <PackageReference Include="PolyShim" Version="1.2.0" PrivateAssets="all" />
+    <PackageReference Include="PolyShim" Version="1.8.0" PrivateAssets="all" />
   </ItemGroup>
 
 </Project>

CliFx.Analyzers/CommandMustBeAnnotatedAnalyzer.cs

@@ -13,14 +13,14 @@ public class CommandMustBeAnnotatedAnalyzer : AnalyzerBase
     public CommandMustBeAnnotatedAnalyzer()
         : base(
             $"Commands must be annotated with `{SymbolNames.CliFxCommandAttribute}`",
-            $"This type must be annotated with `{SymbolNames.CliFxCommandAttribute}` in order to be a valid command.")
-    {
-    }
+            $"This type must be annotated with `{SymbolNames.CliFxCommandAttribute}` in order to be a valid command."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         ClassDeclarationSyntax classDeclaration,
-        ITypeSymbol type)
+        ITypeSymbol type
+    )
     {
         // Ignore abstract classes, because they may be used to define
         // base implementations for commands, in which case the command
@@ -28,12 +28,11 @@ public class CommandMustBeAnnotatedAnalyzer : AnalyzerBase
         if (type.IsAbstract)
             return;
 
-        var implementsCommandInterface = type
-            .AllInterfaces
-            .Any(i => i.DisplayNameMatches(SymbolNames.CliFxCommandInterface));
+        var implementsCommandInterface = type.AllInterfaces.Any(
+            i => i.DisplayNameMatches(SymbolNames.CliFxCommandInterface)
+        );
 
-        var hasCommandAttribute = type
-            .GetAttributes()
+        var hasCommandAttribute = type.GetAttributes()
             .Select(a => a.AttributeClass)
             .Any(c => c.DisplayNameMatches(SymbolNames.CliFxCommandAttribute));
 
@@ -41,9 +40,7 @@ public class CommandMustBeAnnotatedAnalyzer : AnalyzerBase
         // then it's very likely a user error.
         if (implementsCommandInterface && !hasCommandAttribute)
         {
-            context.ReportDiagnostic(
-                CreateDiagnostic(classDeclaration.Identifier.GetLocation())
-            );
+            context.ReportDiagnostic(CreateDiagnostic(classDeclaration.Identifier.GetLocation()));
         }
     }
 
@@ -52,4 +49,4 @@ public class CommandMustBeAnnotatedAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandleClassDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/CommandMustImplementInterfaceAnalyzer.cs

@@ -13,31 +13,28 @@ public class CommandMustImplementInterfaceAnalyzer : AnalyzerBase
     public CommandMustImplementInterfaceAnalyzer()
         : base(
             $"Commands must implement `{SymbolNames.CliFxCommandInterface}` interface",
-            $"This type must implement `{SymbolNames.CliFxCommandInterface}` interface in order to be a valid command.")
-    {
-    }
+            $"This type must implement `{SymbolNames.CliFxCommandInterface}` interface in order to be a valid command."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         ClassDeclarationSyntax classDeclaration,
-        ITypeSymbol type)
+        ITypeSymbol type
+    )
     {
-        var hasCommandAttribute = type
-            .GetAttributes()
+        var hasCommandAttribute = type.GetAttributes()
             .Select(a => a.AttributeClass)
             .Any(c => c.DisplayNameMatches(SymbolNames.CliFxCommandAttribute));
 
-        var implementsCommandInterface = type
-            .AllInterfaces
-            .Any(i => i.DisplayNameMatches(SymbolNames.CliFxCommandInterface));
+        var implementsCommandInterface = type.AllInterfaces.Any(
+            i => i.DisplayNameMatches(SymbolNames.CliFxCommandInterface)
+        );
 
         // If the attribute is present, but the interface is not implemented,
         // it's very likely a user error.
         if (hasCommandAttribute && !implementsCommandInterface)
         {
-            context.ReportDiagnostic(
-                CreateDiagnostic(classDeclaration.Identifier.GetLocation())
-            );
+            context.ReportDiagnostic(CreateDiagnostic(classDeclaration.Identifier.GetLocation()));
         }
     }
 
@@ -46,4 +43,4 @@ public class CommandMustImplementInterfaceAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandleClassDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ObjectModel/CommandOptionSymbol.cs

@@ -25,7 +25,8 @@ internal partial class CommandOptionSymbol : ICommandMemberSymbol
         char? shortName,
         bool? isRequired,
         ITypeSymbol? converterType,
-        IReadOnlyList<ITypeSymbol> validatorTypes)
+        IReadOnlyList<ITypeSymbol> validatorTypes
+    )
     {
         Property = property;
         Name = name;
@@ -38,9 +39,14 @@ internal partial class CommandOptionSymbol : ICommandMemberSymbol
 
 internal partial class CommandOptionSymbol
 {
-    private static AttributeData? TryGetOptionAttribute(IPropertySymbol property) => property
-        .GetAttributes()
-        .FirstOrDefault(a => a.AttributeClass?.DisplayNameMatches(SymbolNames.CliFxCommandOptionAttribute) == true);
+    private static AttributeData? TryGetOptionAttribute(IPropertySymbol property) =>
+        property
+            .GetAttributes()
+            .FirstOrDefault(
+                a =>
+                    a.AttributeClass?.DisplayNameMatches(SymbolNames.CliFxCommandOptionAttribute)
+                    == true
+            );
 
     public static CommandOptionSymbol? TryResolve(IPropertySymbol property)
     {
@@ -48,23 +54,26 @@ internal partial class CommandOptionSymbol
         if (attribute is null)
             return null;
 
-        var name = attribute
-            .ConstructorArguments
-            .Where(a => a.Type?.SpecialType == SpecialType.System_String)
-            .Select(a => a.Value)
-            .FirstOrDefault() as string;
+        var name =
+            attribute
+                .ConstructorArguments
+                .Where(a => a.Type?.SpecialType == SpecialType.System_String)
+                .Select(a => a.Value)
+                .FirstOrDefault() as string;
 
-        var shortName = attribute
-            .ConstructorArguments
-            .Where(a => a.Type?.SpecialType == SpecialType.System_Char)
-            .Select(a => a.Value)
-            .FirstOrDefault() as char?;
+        var shortName =
+            attribute
+                .ConstructorArguments
+                .Where(a => a.Type?.SpecialType == SpecialType.System_Char)
+                .Select(a => a.Value)
+                .FirstOrDefault() as char?;
 
-        var isRequired = attribute
-            .NamedArguments
-            .Where(a => a.Key == "IsRequired")
-            .Select(a => a.Value.Value)
-            .FirstOrDefault() as bool?;
+        var isRequired =
+            attribute
+                .NamedArguments
+                .Where(a => a.Key == "IsRequired")
+                .Select(a => a.Value.Value)
+                .FirstOrDefault() as bool?;
 
         var converter = attribute
             .NamedArguments
@@ -81,9 +90,16 @@ internal partial class CommandOptionSymbol
             .Cast<ITypeSymbol>()
             .ToArray();
 
-        return new CommandOptionSymbol(property, name, shortName, isRequired, converter, validators);
+        return new CommandOptionSymbol(
+            property,
+            name,
+            shortName,
+            isRequired,
+            converter,
+            validators
+        );
     }
 
     public static bool IsOptionProperty(IPropertySymbol property) =>
         TryGetOptionAttribute(property) is not null;
-}
+}

CliFx.Analyzers/ObjectModel/CommandParameterSymbol.cs

@@ -25,7 +25,8 @@ internal partial class CommandParameterSymbol : ICommandMemberSymbol
         string? name,
         bool? isRequired,
         ITypeSymbol? converterType,
-        IReadOnlyList<ITypeSymbol> validatorTypes)
+        IReadOnlyList<ITypeSymbol> validatorTypes
+    )
     {
         Property = property;
         Order = order;
@@ -38,9 +39,14 @@ internal partial class CommandParameterSymbol : ICommandMemberSymbol
 
 internal partial class CommandParameterSymbol
 {
-    private static AttributeData? TryGetParameterAttribute(IPropertySymbol property) => property
-        .GetAttributes()
-        .FirstOrDefault(a => a.AttributeClass?.DisplayNameMatches(SymbolNames.CliFxCommandParameterAttribute) == true);
+    private static AttributeData? TryGetParameterAttribute(IPropertySymbol property) =>
+        property
+            .GetAttributes()
+            .FirstOrDefault(
+                a =>
+                    a.AttributeClass?.DisplayNameMatches(SymbolNames.CliFxCommandParameterAttribute)
+                    == true
+            );
 
     public static CommandParameterSymbol? TryResolve(IPropertySymbol property)
     {
@@ -48,22 +54,21 @@ internal partial class CommandParameterSymbol
         if (attribute is null)
             return null;
 
-        var order = (int)attribute
-            .ConstructorArguments
-            .Select(a => a.Value)
-            .First()!;
+        var order = (int)attribute.ConstructorArguments.Select(a => a.Value).First()!;
 
-        var name = attribute
-            .NamedArguments
-            .Where(a => a.Key == "Name")
-            .Select(a => a.Value.Value)
-            .FirstOrDefault() as string;
+        var name =
+            attribute
+                .NamedArguments
+                .Where(a => a.Key == "Name")
+                .Select(a => a.Value.Value)
+                .FirstOrDefault() as string;
 
-        var isRequired = attribute
-            .NamedArguments
-            .Where(a => a.Key == "IsRequired")
-            .Select(a => a.Value.Value)
-            .FirstOrDefault() as bool?;
+        var isRequired =
+            attribute
+                .NamedArguments
+                .Where(a => a.Key == "IsRequired")
+                .Select(a => a.Value.Value)
+                .FirstOrDefault() as bool?;
 
         var converter = attribute
             .NamedArguments
@@ -85,4 +90,4 @@ internal partial class CommandParameterSymbol
 
     public static bool IsParameterProperty(IPropertySymbol property) =>
         TryGetParameterAttribute(property) is not null;
-}
+}

CliFx.Analyzers/ObjectModel/ICommandMemberSymbol.cs

@@ -16,6 +16,6 @@ internal interface ICommandMemberSymbol
 internal static class CommandMemberSymbolExtensions
 {
     public static bool IsScalar(this ICommandMemberSymbol member) =>
-        member.Property.Type.SpecialType == SpecialType.System_String ||
-        member.Property.Type.TryGetEnumerableUnderlyingType() is null;
-}
+        member.Property.Type.SpecialType == SpecialType.System_String
+        || member.Property.Type.TryGetEnumerableUnderlyingType() is null;
+}

CliFx.Analyzers/ObjectModel/SymbolNames.cs

@@ -4,9 +4,10 @@ internal static class SymbolNames
 {
     public const string CliFxCommandInterface = "CliFx.ICommand";
     public const string CliFxCommandAttribute = "CliFx.Attributes.CommandAttribute";
-    public const string CliFxCommandParameterAttribute = "CliFx.Attributes.CommandParameterAttribute";
+    public const string CliFxCommandParameterAttribute =
+        "CliFx.Attributes.CommandParameterAttribute";
     public const string CliFxCommandOptionAttribute = "CliFx.Attributes.CommandOptionAttribute";
     public const string CliFxConsoleInterface = "CliFx.Infrastructure.IConsole";
     public const string CliFxBindingConverterClass = "CliFx.Extensibility.BindingConverter<T>";
     public const string CliFxBindingValidatorClass = "CliFx.Extensibility.BindingValidator<T>";
-}
+}

CliFx.Analyzers/OptionMustBeInsideCommandAnalyzer.cs

@@ -13,14 +13,14 @@ public class OptionMustBeInsideCommandAnalyzer : AnalyzerBase
     public OptionMustBeInsideCommandAnalyzer()
         : base(
             "Options must be defined inside commands",
-            $"This option must be defined inside a class that implements `{SymbolNames.CliFxCommandInterface}`.")
-    {
-    }
+            $"This option must be defined inside a class that implements `{SymbolNames.CliFxCommandInterface}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -49,4 +49,4 @@ public class OptionMustBeInsideCommandAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustBeRequiredIfPropertyRequiredAnalyzer.cs

@@ -12,14 +12,14 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
     public OptionMustBeRequiredIfPropertyRequiredAnalyzer()
         : base(
             "Options bound to required properties cannot be marked as non-required",
-            "This option cannot be marked as non-required because it's bound to a required property.")
-    {
-    }
+            "This option cannot be marked as non-required because it's bound to a required property."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -34,11 +34,7 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
         if (option.IsRequired != false)
             return;
 
-        context.ReportDiagnostic(
-            CreateDiagnostic(
-                propertyDeclaration.Identifier.GetLocation()
-            )
-        );
+        context.ReportDiagnostic(CreateDiagnostic(propertyDeclaration.Identifier.GetLocation()));
     }
 
     public override void Initialize(AnalysisContext context)
@@ -46,4 +42,4 @@ public class OptionMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveNameOrShortNameAnalyzer.cs

@@ -12,14 +12,14 @@ public class OptionMustHaveNameOrShortNameAnalyzer : AnalyzerBase
     public OptionMustHaveNameOrShortNameAnalyzer()
         : base(
             "Options must have either a name or short name specified",
-            "This option must have either a name or short name specified.")
-    {
-    }
+            "This option must have either a name or short name specified."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var option = CommandOptionSymbol.TryResolve(property);
         if (option is null)
@@ -38,4 +38,4 @@ public class OptionMustHaveNameOrShortNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveUniqueNameAnalyzer.cs

@@ -14,16 +14,16 @@ public class OptionMustHaveUniqueNameAnalyzer : AnalyzerBase
     public OptionMustHaveUniqueNameAnalyzer()
         : base(
             "Options must have unique names",
-            "This option's name must be unique within the command (comparison IS NOT case sensitive). " +
-            "Specified name: `{0}`. " +
-            "Property bound to another option with the same name: `{1}`.")
-    {
-    }
+            "This option's name must be unique within the command (comparison IS NOT case sensitive). "
+                + "Specified name: `{0}`. "
+                + "Property bound to another option with the same name: `{1}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -69,4 +69,4 @@ public class OptionMustHaveUniqueNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveUniqueShortNameAnalyzer.cs

@@ -13,16 +13,16 @@ public class OptionMustHaveUniqueShortNameAnalyzer : AnalyzerBase
     public OptionMustHaveUniqueShortNameAnalyzer()
         : base(
             "Options must have unique short names",
-            "This option's short name must be unique within the command (comparison IS case sensitive). " +
-            "Specified short name: `{0}` " +
-            "Property bound to another option with the same short name: `{1}`.")
-    {
-    }
+            "This option's short name must be unique within the command (comparison IS case sensitive). "
+                + "Specified short name: `{0}` "
+                + "Property bound to another option with the same short name: `{1}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -68,4 +68,4 @@ public class OptionMustHaveUniqueShortNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveValidConverterAnalyzer.cs

@@ -13,14 +13,14 @@ public class OptionMustHaveValidConverterAnalyzer : AnalyzerBase
     public OptionMustHaveValidConverterAnalyzer()
         : base(
             $"Option converters must derive from `{SymbolNames.CliFxBindingConverterClass}`",
-            $"Converter specified for this option must derive from a compatible `{SymbolNames.CliFxBindingConverterClass}`.")
-    {
-    }
+            $"Converter specified for this option must derive from a compatible `{SymbolNames.CliFxBindingConverterClass}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var option = CommandOptionSymbol.TryResolve(property);
         if (option is null)
@@ -32,18 +32,24 @@ public class OptionMustHaveValidConverterAnalyzer : AnalyzerBase
         var converterValueType = option
             .ConverterType
             .GetBaseTypes()
-            .FirstOrDefault(t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingConverterClass))?
-            .TypeArguments
+            .FirstOrDefault(
+                t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingConverterClass)
+            )
+            ?.TypeArguments
             .FirstOrDefault();
 
         // Value returned by the converter must be assignable to the property type
         var isCompatible =
-            converterValueType is not null && (option.IsScalar()
-                // Scalar
-                ? context.Compilation.IsAssignable(converterValueType, property.Type)
-                // Non-scalar (assume we can handle all IEnumerable types for simplicity)
-                : property.Type.TryGetEnumerableUnderlyingType() is { } enumerableUnderlyingType &&
-                  context.Compilation.IsAssignable(converterValueType, enumerableUnderlyingType)
+            converterValueType is not null
+            && (
+                option.IsScalar()
+                    // Scalar
+                    ? context.Compilation.IsAssignable(converterValueType, property.Type)
+                    // Non-scalar (assume we can handle all IEnumerable types for simplicity)
+                    : property.Type.TryGetEnumerableUnderlyingType() is { } enumerableUnderlyingType
+                        && context
+                            .Compilation
+                            .IsAssignable(converterValueType, enumerableUnderlyingType)
             );
 
         if (!isCompatible)
@@ -59,4 +65,4 @@ public class OptionMustHaveValidConverterAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveValidNameAnalyzer.cs

@@ -12,15 +12,15 @@ public class OptionMustHaveValidNameAnalyzer : AnalyzerBase
     public OptionMustHaveValidNameAnalyzer()
         : base(
             "Options must have valid names",
-            "This option's name must be at least 2 characters long and must start with a letter. " +
-            "Specified name: `{0}`.")
-    {
-    }
+            "This option's name must be at least 2 characters long and must start with a letter. "
+                + "Specified name: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var option = CommandOptionSymbol.TryResolve(property);
         if (option is null)
@@ -32,10 +32,7 @@ public class OptionMustHaveValidNameAnalyzer : AnalyzerBase
         if (option.Name.Length < 2 || !char.IsLetter(option.Name[0]))
         {
             context.ReportDiagnostic(
-                CreateDiagnostic(
-                    propertyDeclaration.Identifier.GetLocation(),
-                    option.Name
-                )
+                CreateDiagnostic(propertyDeclaration.Identifier.GetLocation(), option.Name)
             );
         }
     }
@@ -45,4 +42,4 @@ public class OptionMustHaveValidNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveValidShortNameAnalyzer.cs

@@ -12,15 +12,15 @@ public class OptionMustHaveValidShortNameAnalyzer : AnalyzerBase
     public OptionMustHaveValidShortNameAnalyzer()
         : base(
             "Option short names must be letter characters",
-            "This option's short name must be a single letter character. " +
-            "Specified short name: `{0}`.")
-    {
-    }
+            "This option's short name must be a single letter character. "
+                + "Specified short name: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var option = CommandOptionSymbol.TryResolve(property);
         if (option is null)
@@ -32,10 +32,7 @@ public class OptionMustHaveValidShortNameAnalyzer : AnalyzerBase
         if (!char.IsLetter(option.ShortName.Value))
         {
             context.ReportDiagnostic(
-                CreateDiagnostic(
-                    propertyDeclaration.Identifier.GetLocation(),
-                    option.ShortName
-                )
+                CreateDiagnostic(propertyDeclaration.Identifier.GetLocation(), option.ShortName)
             );
         }
     }
@@ -45,4 +42,4 @@ public class OptionMustHaveValidShortNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/OptionMustHaveValidValidatorsAnalyzer.cs

@@ -13,14 +13,14 @@ public class OptionMustHaveValidValidatorsAnalyzer : AnalyzerBase
     public OptionMustHaveValidValidatorsAnalyzer()
         : base(
             $"Option validators must derive from `{SymbolNames.CliFxBindingValidatorClass}`",
-            $"Each validator specified for this option must derive from a compatible `{SymbolNames.CliFxBindingValidatorClass}`.")
-    {
-    }
+            $"Each validator specified for this option must derive from a compatible `{SymbolNames.CliFxBindingValidatorClass}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var option = CommandOptionSymbol.TryResolve(property);
         if (option is null)
@@ -30,14 +30,17 @@ public class OptionMustHaveValidValidatorsAnalyzer : AnalyzerBase
         {
             var validatorValueType = validatorType
                 .GetBaseTypes()
-                .FirstOrDefault(t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingValidatorClass))?
-                .TypeArguments
+                .FirstOrDefault(
+                    t =>
+                        t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingValidatorClass)
+                )
+                ?.TypeArguments
                 .FirstOrDefault();
 
             // Value passed to the validator must be assignable from the property type
             var isCompatible =
-                validatorValueType is not null &&
-                context.Compilation.IsAssignable(property.Type, validatorValueType);
+                validatorValueType is not null
+                && context.Compilation.IsAssignable(property.Type, validatorValueType);
 
             if (!isCompatible)
             {
@@ -56,4 +59,4 @@ public class OptionMustHaveValidValidatorsAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeInsideCommandAnalyzer.cs

@@ -13,14 +13,14 @@ public class ParameterMustBeInsideCommandAnalyzer : AnalyzerBase
     public ParameterMustBeInsideCommandAnalyzer()
         : base(
             "Parameters must be defined inside commands",
-            $"This parameter must be defined inside a class that implements `{SymbolNames.CliFxCommandInterface}`.")
-    {
-    }
+            $"This parameter must be defined inside a class that implements `{SymbolNames.CliFxCommandInterface}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -49,4 +49,4 @@ public class ParameterMustBeInsideCommandAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeLastIfNonRequiredAnalyzer.cs

@@ -13,15 +13,15 @@ public class ParameterMustBeLastIfNonRequiredAnalyzer : AnalyzerBase
     public ParameterMustBeLastIfNonRequiredAnalyzer()
         : base(
             "Parameters marked as non-required must be the last in order",
-            "This parameter is non-required so it must be the last in order (its order must be highest within the command). " +
-            "Property bound to another non-required parameter: `{0}`.")
-    {
-    }
+            "This parameter is non-required so it must be the last in order (its order must be highest within the command). "
+                + "Property bound to another non-required parameter: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -63,4 +63,4 @@ public class ParameterMustBeLastIfNonRequiredAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeLastIfNonScalarAnalyzer.cs

@@ -13,15 +13,15 @@ public class ParameterMustBeLastIfNonScalarAnalyzer : AnalyzerBase
     public ParameterMustBeLastIfNonScalarAnalyzer()
         : base(
             "Parameters of non-scalar types must be the last in order",
-            "This parameter has a non-scalar type so it must be the last in order (its order must be highest within the command). " +
-            "Property bound to another non-scalar parameter: `{0}`.")
-    {
-    }
+            "This parameter has a non-scalar type so it must be the last in order (its order must be highest within the command). "
+                + "Property bound to another non-scalar parameter: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -63,4 +63,4 @@ public class ParameterMustBeLastIfNonScalarAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeRequiredIfPropertyRequiredAnalyzer.cs

@@ -12,14 +12,14 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
     public ParameterMustBeRequiredIfPropertyRequiredAnalyzer()
         : base(
             "Parameters bound to required properties cannot be marked as non-required",
-            "This parameter cannot be marked as non-required because it's bound to a required property.")
-    {
-    }
+            "This parameter cannot be marked as non-required because it's bound to a required property."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -34,11 +34,7 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
         if (parameter.IsRequired != false)
             return;
 
-        context.ReportDiagnostic(
-            CreateDiagnostic(
-                propertyDeclaration.Identifier.GetLocation()
-            )
-        );
+        context.ReportDiagnostic(CreateDiagnostic(propertyDeclaration.Identifier.GetLocation()));
     }
 
     public override void Initialize(AnalysisContext context)
@@ -46,4 +42,4 @@ public class ParameterMustBeRequiredIfPropertyRequiredAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeSingleIfNonRequiredAnalyzer.cs

@@ -13,15 +13,15 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzer : AnalyzerBase
     public ParameterMustBeSingleIfNonRequiredAnalyzer()
         : base(
             "Parameters marked as non-required are limited to one per command",
-            "This parameter is non-required so it must be the only such parameter in the command. " +
-            "Property bound to another non-required parameter: `{0}`.")
-    {
-    }
+            "This parameter is non-required so it must be the only such parameter in the command. "
+                + "Property bound to another non-required parameter: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -63,4 +63,4 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustBeSingleIfNonScalarAnalyzer.cs

@@ -13,15 +13,15 @@ public class ParameterMustBeSingleIfNonScalarAnalyzer : AnalyzerBase
     public ParameterMustBeSingleIfNonScalarAnalyzer()
         : base(
             "Parameters of non-scalar types are limited to one per command",
-            "This parameter has a non-scalar type so it must be the only such parameter in the command. " +
-            "Property bound to another non-scalar parameter: `{0}`.")
-    {
-    }
+            "This parameter has a non-scalar type so it must be the only such parameter in the command. "
+                + "Property bound to another non-scalar parameter: `{0}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -63,4 +63,4 @@ public class ParameterMustBeSingleIfNonScalarAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustHaveUniqueNameAnalyzer.cs

@@ -14,16 +14,16 @@ public class ParameterMustHaveUniqueNameAnalyzer : AnalyzerBase
     public ParameterMustHaveUniqueNameAnalyzer()
         : base(
             "Parameters must have unique names",
-            "This parameter's name must be unique within the command (comparison IS NOT case sensitive). " +
-            "Specified name: `{0}`. " +
-            "Property bound to another parameter with the same name: `{1}`.")
-    {
-    }
+            "This parameter's name must be unique within the command (comparison IS NOT case sensitive). "
+                + "Specified name: `{0}`. "
+                + "Property bound to another parameter with the same name: `{1}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -51,7 +51,13 @@ public class ParameterMustHaveUniqueNameAnalyzer : AnalyzerBase
             if (string.IsNullOrWhiteSpace(otherParameter.Name))
                 continue;
 
-            if (string.Equals(parameter.Name, otherParameter.Name, StringComparison.OrdinalIgnoreCase))
+            if (
+                string.Equals(
+                    parameter.Name,
+                    otherParameter.Name,
+                    StringComparison.OrdinalIgnoreCase
+                )
+            )
             {
                 context.ReportDiagnostic(
                     CreateDiagnostic(
@@ -69,4 +75,4 @@ public class ParameterMustHaveUniqueNameAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustHaveUniqueOrderAnalyzer.cs

@@ -13,16 +13,16 @@ public class ParameterMustHaveUniqueOrderAnalyzer : AnalyzerBase
     public ParameterMustHaveUniqueOrderAnalyzer()
         : base(
             "Parameters must have unique order",
-            "This parameter's order must be unique within the command. " +
-            "Specified order: {0}. " +
-            "Property bound to another parameter with the same order: `{1}`.")
-    {
-    }
+            "This parameter's order must be unique within the command. "
+                + "Specified order: {0}. "
+                + "Property bound to another parameter with the same order: `{1}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         if (property.ContainingType is null)
             return;
@@ -62,4 +62,4 @@ public class ParameterMustHaveUniqueOrderAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustHaveValidConverterAnalyzer.cs

@@ -13,14 +13,14 @@ public class ParameterMustHaveValidConverterAnalyzer : AnalyzerBase
     public ParameterMustHaveValidConverterAnalyzer()
         : base(
             $"Parameter converters must derive from `{SymbolNames.CliFxBindingConverterClass}`",
-            $"Converter specified for this parameter must derive from a compatible `{SymbolNames.CliFxBindingConverterClass}`.")
-    {
-    }
+            $"Converter specified for this parameter must derive from a compatible `{SymbolNames.CliFxBindingConverterClass}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var parameter = CommandParameterSymbol.TryResolve(property);
         if (parameter is null)
@@ -32,18 +32,24 @@ public class ParameterMustHaveValidConverterAnalyzer : AnalyzerBase
         var converterValueType = parameter
             .ConverterType
             .GetBaseTypes()
-            .FirstOrDefault(t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingConverterClass))?
-            .TypeArguments
+            .FirstOrDefault(
+                t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingConverterClass)
+            )
+            ?.TypeArguments
             .FirstOrDefault();
 
         // Value returned by the converter must be assignable to the property type
         var isCompatible =
-            converterValueType is not null && (parameter.IsScalar()
-                // Scalar
-                ? context.Compilation.IsAssignable(converterValueType, property.Type)
-                // Non-scalar (assume we can handle all IEnumerable types for simplicity)
-                : property.Type.TryGetEnumerableUnderlyingType() is { } enumerableUnderlyingType &&
-                  context.Compilation.IsAssignable(converterValueType, enumerableUnderlyingType)
+            converterValueType is not null
+            && (
+                parameter.IsScalar()
+                    // Scalar
+                    ? context.Compilation.IsAssignable(converterValueType, property.Type)
+                    // Non-scalar (assume we can handle all IEnumerable types for simplicity)
+                    : property.Type.TryGetEnumerableUnderlyingType() is { } enumerableUnderlyingType
+                        && context
+                            .Compilation
+                            .IsAssignable(converterValueType, enumerableUnderlyingType)
             );
 
         if (!isCompatible)
@@ -59,4 +65,4 @@ public class ParameterMustHaveValidConverterAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/ParameterMustHaveValidValidatorsAnalyzer.cs

@@ -13,14 +13,14 @@ public class ParameterMustHaveValidValidatorsAnalyzer : AnalyzerBase
     public ParameterMustHaveValidValidatorsAnalyzer()
         : base(
             $"Parameter validators must derive from `{SymbolNames.CliFxBindingValidatorClass}`",
-            $"Each validator specified for this parameter must derive from a compatible `{SymbolNames.CliFxBindingValidatorClass}`.")
-    {
-    }
+            $"Each validator specified for this parameter must derive from a compatible `{SymbolNames.CliFxBindingValidatorClass}`."
+        ) { }
 
     private void Analyze(
         SyntaxNodeAnalysisContext context,
         PropertyDeclarationSyntax propertyDeclaration,
-        IPropertySymbol property)
+        IPropertySymbol property
+    )
     {
         var parameter = CommandParameterSymbol.TryResolve(property);
         if (parameter is null)
@@ -30,14 +30,17 @@ public class ParameterMustHaveValidValidatorsAnalyzer : AnalyzerBase
         {
             var validatorValueType = validatorType
                 .GetBaseTypes()
-                .FirstOrDefault(t => t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingValidatorClass))?
-                .TypeArguments
+                .FirstOrDefault(
+                    t =>
+                        t.ConstructedFrom.DisplayNameMatches(SymbolNames.CliFxBindingValidatorClass)
+                )
+                ?.TypeArguments
                 .FirstOrDefault();
 
             // Value passed to the validator must be assignable from the property type
             var isCompatible =
-                validatorValueType is not null &&
-                context.Compilation.IsAssignable(property.Type, validatorValueType);
+                validatorValueType is not null
+                && context.Compilation.IsAssignable(property.Type, validatorValueType);
 
             if (!isCompatible)
             {
@@ -56,4 +59,4 @@ public class ParameterMustHaveValidValidatorsAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.HandlePropertyDeclaration(Analyze);
     }
-}
+}

CliFx.Analyzers/SystemConsoleShouldBeAvoidedAnalyzer.cs

@@ -15,13 +15,13 @@ public class SystemConsoleShouldBeAvoidedAnalyzer : AnalyzerBase
         : base(
             $"Avoid calling `System.Console` where `{SymbolNames.CliFxConsoleInterface}` is available",
             $"Use the provided `{SymbolNames.CliFxConsoleInterface}` abstraction instead of `System.Console` to ensure that the command can be tested in isolation.",
-            DiagnosticSeverity.Warning)
-    {
-    }
+            DiagnosticSeverity.Warning
+        ) { }
 
     private MemberAccessExpressionSyntax? TryGetSystemConsoleMemberAccess(
         SyntaxNodeAnalysisContext context,
-        SyntaxNode node)
+        SyntaxNode node
+    )
     {
         var currentNode = node;
 
@@ -65,9 +65,7 @@ public class SystemConsoleShouldBeAvoidedAnalyzer : AnalyzerBase
 
         if (isConsoleInterfaceAvailable)
         {
-            context.ReportDiagnostic(
-                CreateDiagnostic(systemConsoleMemberAccess.GetLocation())
-            );
+            context.ReportDiagnostic(CreateDiagnostic(systemConsoleMemberAccess.GetLocation()));
         }
     }
 
@@ -76,4 +74,4 @@ public class SystemConsoleShouldBeAvoidedAnalyzer : AnalyzerBase
         base.Initialize(context);
         context.RegisterSyntaxNodeAction(Analyze, SyntaxKind.SimpleMemberAccessExpression);
     }
-}
+}

CliFx.Analyzers/Utils/Extensions/RoslynExtensions.cs

@@ -29,56 +29,72 @@ internal static class RoslynExtensions
         }
     }
 
-    public static ITypeSymbol? TryGetEnumerableUnderlyingType(this ITypeSymbol type) => type
-        .AllInterfaces
-        .FirstOrDefault(i => i.ConstructedFrom.SpecialType == SpecialType.System_Collections_Generic_IEnumerable_T)?
-        .TypeArguments[0];
+    public static ITypeSymbol? TryGetEnumerableUnderlyingType(this ITypeSymbol type) =>
+        type.AllInterfaces
+            .FirstOrDefault(
+                i =>
+                    i.ConstructedFrom.SpecialType
+                    == SpecialType.System_Collections_Generic_IEnumerable_T
+            )
+            ?.TypeArguments[0];
 
     // Detect if the property is required through roundabout means so as to not have to take dependency
     // on higher versions of the C# compiler.
-    public static bool IsRequired(this IPropertySymbol property) => property
-        // Can't rely on the RequiredMemberAttribute because it's generated by the compiler, not added by the user,
-        // so we have to check for the presence of the `required` modifier in the syntax tree instead.
-        .DeclaringSyntaxReferences
-        .Select(r => r.GetSyntax())
-        .OfType<PropertyDeclarationSyntax>()
-        .SelectMany(p => p.Modifiers)
-        .Any(m => m.IsKind((SyntaxKind)8447));
+    public static bool IsRequired(this IPropertySymbol property) =>
+        property
+            // Can't rely on the RequiredMemberAttribute because it's generated by the compiler, not added by the user,
+            // so we have to check for the presence of the `required` modifier in the syntax tree instead.
+            .DeclaringSyntaxReferences
+            .Select(r => r.GetSyntax())
+            .OfType<PropertyDeclarationSyntax>()
+            .SelectMany(p => p.Modifiers)
+            .Any(m => m.IsKind((SyntaxKind)8447));
 
-    public static bool IsAssignable(this Compilation compilation, ITypeSymbol source, ITypeSymbol destination) =>
-        compilation.ClassifyConversion(source, destination).Exists;
+    public static bool IsAssignable(
+        this Compilation compilation,
+        ITypeSymbol source,
+        ITypeSymbol destination
+    ) => compilation.ClassifyConversion(source, destination).Exists;
 
     public static void HandleClassDeclaration(
         this AnalysisContext analysisContext,
-        Action<SyntaxNodeAnalysisContext, ClassDeclarationSyntax, ITypeSymbol> analyze)
+        Action<SyntaxNodeAnalysisContext, ClassDeclarationSyntax, ITypeSymbol> analyze
+    )
     {
-        analysisContext.RegisterSyntaxNodeAction(ctx =>
-        {
-            if (ctx.Node is not ClassDeclarationSyntax classDeclaration)
-                return;
+        analysisContext.RegisterSyntaxNodeAction(
+            ctx =>
+            {
+                if (ctx.Node is not ClassDeclarationSyntax classDeclaration)
+                    return;
 
-            var type = ctx.SemanticModel.GetDeclaredSymbol(classDeclaration);
-            if (type is null)
-                return;
+                var type = ctx.SemanticModel.GetDeclaredSymbol(classDeclaration);
+                if (type is null)
+                    return;
 
-            analyze(ctx, classDeclaration, type);
-        }, SyntaxKind.ClassDeclaration);
+                analyze(ctx, classDeclaration, type);
+            },
+            SyntaxKind.ClassDeclaration
+        );
     }
 
     public static void HandlePropertyDeclaration(
         this AnalysisContext analysisContext,
-        Action<SyntaxNodeAnalysisContext, PropertyDeclarationSyntax, IPropertySymbol> analyze)
+        Action<SyntaxNodeAnalysisContext, PropertyDeclarationSyntax, IPropertySymbol> analyze
+    )
     {
-        analysisContext.RegisterSyntaxNodeAction(ctx =>
-        {
-            if (ctx.Node is not PropertyDeclarationSyntax propertyDeclaration)
-                return;
+        analysisContext.RegisterSyntaxNodeAction(
+            ctx =>
+            {
+                if (ctx.Node is not PropertyDeclarationSyntax propertyDeclaration)
+                    return;
 
-            var property = ctx.SemanticModel.GetDeclaredSymbol(propertyDeclaration);
-            if (property is null)
-                return;
+                var property = ctx.SemanticModel.GetDeclaredSymbol(propertyDeclaration);
+                if (property is null)
+                    return;
 
-            analyze(ctx, propertyDeclaration, property);
-        }, SyntaxKind.PropertyDeclaration);
+                analyze(ctx, propertyDeclaration, property);
+            },
+            SyntaxKind.PropertyDeclaration
+        );
     }
-}
+}

CliFx.Analyzers/Utils/Extensions/StringExtensions.cs

@@ -7,11 +7,12 @@ internal static class StringExtensions
     public static string TrimEnd(
         this string str,
         string sub,
-        StringComparison comparison = StringComparison.Ordinal)
+        StringComparison comparison = StringComparison.Ordinal
+    )
     {
         while (str.EndsWith(sub, comparison))
             str = str[..^sub.Length];
 
         return str;
     }
-}
+}

CliFx.Benchmarks/Benchmarks.CliFx.cs

@@ -29,4 +29,4 @@ public partial class Benchmarks
             .AddCommand<CliFxCommand>()
             .Build()
             .RunAsync(Arguments, new Dictionary<string, string>());
-}
+}

CliFx.Benchmarks/Benchmarks.Clipr.cs

@@ -16,11 +16,9 @@ public partial class Benchmarks
         [NamedArgument('b', "bool", Constraint = NumArgsConstraint.Optional, Const = true)]
         public bool BoolOption { get; set; }
 
-        public void Execute()
-        {
-        }
+        public void Execute() { }
     }
 
     [Benchmark(Description = "Clipr")]
     public void ExecuteWithClipr() => CliParser.Parse<CliprCommand>(Arguments).Execute();
-}
+}

CliFx.Benchmarks/Benchmarks.Cocona.cs

@@ -8,16 +8,12 @@ public partial class Benchmarks
     public class CoconaCommand
     {
         public void Execute(
-            [Option("str", new []{'s'})]
-            string? strOption,
-            [Option("int", new []{'i'})]
-            int intOption,
-            [Option("bool", new []{'b'})]
-            bool boolOption)
-        {
-        }
+            [Option("str", new[] { 's' })] string? strOption,
+            [Option("int", new[] { 'i' })] int intOption,
+            [Option("bool", new[] { 'b' })] bool boolOption
+        ) { }
     }
 
     [Benchmark(Description = "Cocona")]
     public void ExecuteWithCocona() => CoconaApp.Run<CoconaCommand>(Arguments);
-}
+}

CliFx.Benchmarks/Benchmarks.CommandLineParser.cs

@@ -16,9 +16,7 @@ public partial class Benchmarks
         [Option('b', "bool")]
         public bool BoolOption { get; set; }
 
-        public void Execute()
-        {
-        }
+        public void Execute() { }
     }
 
     [Benchmark(Description = "CommandLineParser")]
@@ -26,4 +24,4 @@ public partial class Benchmarks
         new Parser()
             .ParseArguments(Arguments, typeof(CommandLineParserCommand))
             .WithParsed<CommandLineParserCommand>(c => c.Execute());
-}
+}

CliFx.Benchmarks/Benchmarks.McMaster.cs

@@ -21,4 +21,4 @@ public partial class Benchmarks
 
     [Benchmark(Description = "McMaster.Extensions.CommandLineUtils")]
     public int ExecuteWithMcMaster() => CommandLineApplication.Execute<McMasterCommand>(Arguments);
-}
+}

CliFx.Benchmarks/Benchmarks.PowerArgs.cs

@@ -16,11 +16,9 @@ public partial class Benchmarks
         [ArgShortcut("--bool"), ArgShortcut("-b")]
         public bool BoolOption { get; set; }
 
-        public void Main()
-        {
-        }
+        public void Main() { }
     }
 
     [Benchmark(Description = "PowerArgs")]
     public void ExecuteWithPowerArgs() => Args.InvokeMain<PowerArgsCommand>(Arguments);
-}
+}

CliFx.Benchmarks/Benchmarks.SystemCommandLine.cs

@@ -15,18 +15,9 @@ public partial class Benchmarks
         {
             var command = new RootCommand
             {
-                new Option(new[] {"--str", "-s"})
-                {
-                    Argument = new Argument<string?>()
-                },
-                new Option(new[] {"--int", "-i"})
-                {
-                    Argument = new Argument<int>()
-                },
-                new Option(new[] {"--bool", "-b"})
-                {
-                    Argument = new Argument<bool>()
-                }
+                new Option(new[] { "--str", "-s" }) { Argument = new Argument<string?>() },
+                new Option(new[] { "--int", "-i" }) { Argument = new Argument<int>() },
+                new Option(new[] { "--bool", "-b" }) { Argument = new Argument<bool>() }
             };
 
             command.Handler = CommandHandler.Create(
@@ -40,4 +31,4 @@ public partial class Benchmarks
     [Benchmark(Description = "System.CommandLine")]
     public async Task<int> ExecuteWithSystemCommandLine() =>
         await new SystemCommandLineCommand().ExecuteAsync(Arguments);
-}
+}

CliFx.Benchmarks/Benchmarks.cs

@@ -9,11 +9,10 @@ namespace CliFx.Benchmarks;
 [Orderer(SummaryOrderPolicy.FastestToSlowest)]
 public partial class Benchmarks
 {
-    private static readonly string[] Arguments = {"--str", "hello world", "-i", "13", "-b"};
+    private static readonly string[] Arguments = { "--str", "hello world", "-i", "13", "-b" };
 
-    public static void Main() => BenchmarkRunner.Run<Benchmarks>(
-        DefaultConfig
-            .Instance
-            .WithOptions(ConfigOptions.DisableOptimizationsValidator)
-    );
-}
+    public static void Main() =>
+        BenchmarkRunner.Run<Benchmarks>(
+            DefaultConfig.Instance.WithOptions(ConfigOptions.DisableOptimizationsValidator)
+        );
+}

CliFx.Benchmarks/CliFx.Benchmarks.csproj

@@ -2,16 +2,17 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.13.5" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.13.10" />
     <PackageReference Include="clipr" Version="1.6.1" />
     <PackageReference Include="Cocona" Version="2.2.0" />
     <PackageReference Include="CommandLineParser" Version="2.9.1" />
-    <PackageReference Include="McMaster.Extensions.CommandLineUtils" Version="4.0.2" />
-    <PackageReference Include="PowerArgs" Version="4.0.2" />
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
+    <PackageReference Include="McMaster.Extensions.CommandLineUtils" Version="4.1.0" />
+    <PackageReference Include="PowerArgs" Version="4.0.3" />
     <PackageReference Include="System.CommandLine" Version="2.0.0-beta1.20574.7" />
   </ItemGroup>
 

CliFx.Demo/CliFx.Demo.csproj

@@ -2,11 +2,13 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
+    <ApplicationIcon>../favicon.ico</ApplicationIcon>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="7.0.0" />
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0" />
   </ItemGroup>
 
   <ItemGroup>

CliFx.Demo/Commands/BookAddCommand.cs

@@ -8,7 +8,7 @@ using CliFx.Infrastructure;
 
 namespace CliFx.Demo.Commands;
 
-[Command("book add", Description = "Add a book to the library.")]
+[Command("book add", Description = "Adds a book to the library.")]
 public partial class BookAddCommand : ICommand
 {
     private readonly LibraryProvider _libraryProvider;
@@ -16,7 +16,7 @@ public partial class BookAddCommand : ICommand
     [CommandParameter(0, Name = "title", Description = "Book title.")]
     public required string Title { get; init; }
 
-    [CommandOption("author", 'a', IsRequired = true, Description = "Book author.")]
+    [CommandOption("author", 'a', Description = "Book author.")]
     public required string Author { get; init; }
 
     [CommandOption("published", 'p', Description = "Book publish date.")]
@@ -49,21 +49,23 @@ public partial class BookAddCommand
 {
     private static readonly Random Random = new();
 
-    private static DateTimeOffset CreateRandomDate() => new(
-        Random.Next(1800, 2020),
-        Random.Next(1, 12),
-        Random.Next(1, 28),
-        Random.Next(1, 23),
-        Random.Next(1, 59),
-        Random.Next(1, 59),
-        TimeSpan.Zero
-    );
+    private static DateTimeOffset CreateRandomDate() =>
+        new(
+            Random.Next(1800, 2020),
+            Random.Next(1, 12),
+            Random.Next(1, 28),
+            Random.Next(1, 23),
+            Random.Next(1, 59),
+            Random.Next(1, 59),
+            TimeSpan.Zero
+        );
 
-    private static Isbn CreateRandomIsbn() => new(
-        Random.Next(0, 999),
-        Random.Next(0, 99),
-        Random.Next(0, 99999),
-        Random.Next(0, 99),
-        Random.Next(0, 9)
-    );
-}
+    private static Isbn CreateRandomIsbn() =>
+        new(
+            Random.Next(0, 999),
+            Random.Next(0, 99),
+            Random.Next(0, 99999),
+            Random.Next(0, 99),
+            Random.Next(0, 9)
+        );
+}

CliFx.Demo/Commands/BookCommand.cs

@@ -7,7 +7,7 @@ using CliFx.Infrastructure;
 
 namespace CliFx.Demo.Commands;
 
-[Command("book", Description = "Retrieve a book from the library.")]
+[Command("book", Description = "Retrieves a book from the library.")]
 public class BookCommand : ICommand
 {
     private readonly LibraryProvider _libraryProvider;
@@ -31,4 +31,4 @@ public class BookCommand : ICommand
 
         return default;
     }
-}
+}

CliFx.Demo/Commands/BookListCommand.cs

@@ -6,7 +6,7 @@ using CliFx.Infrastructure;
 
 namespace CliFx.Demo.Commands;
 
-[Command("book list", Description = "List all books in the library.")]
+[Command("book list", Description = "Lists all books in the library.")]
 public class BookListCommand : ICommand
 {
     private readonly LibraryProvider _libraryProvider;
@@ -33,4 +33,4 @@ public class BookListCommand : ICommand
 
         return default;
     }
-}
+}

CliFx.Demo/Commands/BookRemoveCommand.cs

@@ -6,7 +6,7 @@ using CliFx.Infrastructure;
 
 namespace CliFx.Demo.Commands;
 
-[Command("book remove", Description = "Remove a book from the library.")]
+[Command("book remove", Description = "Removes a book from the library.")]
 public class BookRemoveCommand : ICommand
 {
     private readonly LibraryProvider _libraryProvider;
@@ -32,4 +32,4 @@ public class BookRemoveCommand : ICommand
 
         return default;
     }
-}
+}

CliFx.Demo/Domain/Book.cs

@@ -2,4 +2,4 @@
 
 namespace CliFx.Demo.Domain;
 
-public record Book(string Title, string Author, DateTimeOffset Published, Isbn Isbn);
+public record Book(string Title, string Author, DateTimeOffset Published, Isbn Isbn);

CliFx.Demo/Domain/Isbn.cs

@@ -2,7 +2,13 @@
 
 namespace CliFx.Demo.Domain;
 
-public partial record Isbn(int EanPrefix, int RegistrationGroup, int Registrant, int Publication, int CheckDigit)
+public partial record Isbn(
+    int EanPrefix,
+    int RegistrationGroup,
+    int Registrant,
+    int Publication,
+    int CheckDigit
+)
 {
     public override string ToString() =>
         $"{EanPrefix:000}-{RegistrationGroup:00}-{Registrant:00000}-{Publication:00}-{CheckDigit:0}";
@@ -22,4 +28,4 @@ public partial record Isbn
             int.Parse(components[4], formatProvider)
         );
     }
-}
+}

CliFx.Demo/Domain/Library.cs

@@ -25,4 +25,4 @@ public partial record Library(IReadOnlyList<Book> Books)
 public partial record Library
 {
     public static Library Empty { get; } = new(Array.Empty<Book>());
-}
+}

CliFx.Demo/Domain/LibraryProvider.cs

@@ -6,7 +6,8 @@ namespace CliFx.Demo.Domain;
 
 public class LibraryProvider
 {
-    private static string StorageFilePath { get; } = Path.Combine(Directory.GetCurrentDirectory(), "Library.json");
+    private static string StorageFilePath { get; } =
+        Path.Combine(Directory.GetCurrentDirectory(), "Library.json");
 
     private void StoreLibrary(Library library)
     {
@@ -24,7 +25,8 @@ public class LibraryProvider
         return JsonSerializer.Deserialize<Library>(data) ?? Library.Empty;
     }
 
-    public Book? TryGetBook(string title) => GetLibrary().Books.FirstOrDefault(b => b.Title == title);
+    public Book? TryGetBook(string title) =>
+        GetLibrary().Books.FirstOrDefault(b => b.Title == title);
 
     public void AddBook(Book book)
     {
@@ -37,4 +39,4 @@ public class LibraryProvider
         var updatedLibrary = GetLibrary().WithoutBook(book);
         StoreLibrary(updatedLibrary);
     }
-}
+}

CliFx.Demo/Program.cs

@@ -1,25 +1,21 @@
 using CliFx;
-using CliFx.Demo.Commands;
 using CliFx.Demo.Domain;
 using Microsoft.Extensions.DependencyInjection;
 
-// We use Microsoft.Extensions.DependencyInjection for injecting dependencies in commands
-var services = new ServiceCollection();
-
-// Register services
-services.AddSingleton<LibraryProvider>();
-
-// Register commands
-services.AddTransient<BookCommand>();
-services.AddTransient<BookAddCommand>();
-services.AddTransient<BookRemoveCommand>();
-services.AddTransient<BookListCommand>();
-
-var serviceProvider = services.BuildServiceProvider();
-
 return await new CliApplicationBuilder()
     .SetDescription("Demo application showcasing CliFx features.")
     .AddCommandsFromThisAssembly()
-    .UseTypeActivator(serviceProvider.GetRequiredService)
+    .UseTypeActivator(commandTypes =>
+    {
+        // We use Microsoft.Extensions.DependencyInjection for injecting dependencies in commands
+        var services = new ServiceCollection();
+        services.AddSingleton<LibraryProvider>();
+
+        // Register all commands as transient services
+        foreach (var commandType in commandTypes)
+            services.AddTransient(commandType);
+
+        return services.BuildServiceProvider();
+    })
     .Build()
-    .RunAsync();
+    .RunAsync();

CliFx.Demo/Utils/ConsoleExtensions.cs

@@ -33,4 +33,4 @@ internal static class ConsoleExtensions
         using (writer.Console.WithForegroundColor(ConsoleColor.White))
             writer.WriteLine(book.Isbn);
     }
-}
+}

CliFx.Tests.Dummy/CliFx.Tests.Dummy.csproj

@@ -2,9 +2,14 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
+    <ApplicationIcon>../favicon.ico</ApplicationIcon>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
+  </ItemGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\CliFx\CliFx.csproj" />
     <ProjectReference Include="..\CliFx.Analyzers\CliFx.Analyzers.csproj" ReferenceOutputAssembly="false" OutputItemType="analyzer" />

CliFx.Tests.Dummy/Commands/CancellationTestCommand.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Threading.Tasks;
+using CliFx.Attributes;
+using CliFx.Infrastructure;
+
+namespace CliFx.Tests.Dummy.Commands;
+
+[Command("cancel-test")]
+public class CancellationTestCommand : ICommand
+{
+    public async ValueTask ExecuteAsync(IConsole console)
+    {
+        try
+        {
+            console.Output.WriteLine("Started.");
+
+            await Task.Delay(TimeSpan.FromSeconds(3), console.RegisterCancellationHandler());
+
+            console.Output.WriteLine("Completed.");
+        }
+        catch (OperationCanceledException)
+        {
+            console.Output.WriteLine("Cancelled.");
+            throw;
+        }
+    }
+}

CliFx.Tests.Dummy/Commands/ConsoleTestCommand.cs

@@ -20,4 +20,4 @@ public class ConsoleTestCommand : ICommand
 
         return default;
     }
-}
+}

CliFx.Tests.Dummy/Commands/EnvironmentTestCommand.cs

@@ -8,7 +8,7 @@ namespace CliFx.Tests.Dummy.Commands;
 public class EnvironmentTestCommand : ICommand
 {
     [CommandOption("target", EnvironmentVariable = "ENV_TARGET")]
-    public string GreetingTarget { get; set; } = "World";
+    public string GreetingTarget { get; init; } = "World";
 
     public ValueTask ExecuteAsync(IConsole console)
     {
@@ -16,4 +16,4 @@ public class EnvironmentTestCommand : ICommand
 
         return default;
     }
-}
+}

CliFx.Tests.Dummy/Program.cs

@@ -1,21 +1,21 @@
 using System;
+using System.IO;
 using System.Reflection;
+using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 
 namespace CliFx.Tests.Dummy;
 
-// This dummy application is used in tests for scenarios
-// that require an external process to properly verify.
-
-public static partial class Program
+// This dummy application is used in tests for scenarios that require an external process to properly verify
+public static class Program
 {
-    public static Assembly Assembly { get; } = Assembly.GetExecutingAssembly();
+    // Path to the apphost
+    public static string FilePath { get; } =
+        Path.ChangeExtension(
+            Assembly.GetExecutingAssembly().Location,
+            RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? "exe" : null
+        );
 
-    public static string Location { get; } = Assembly.Location;
-}
-
-public static partial class Program
-{
     public static async Task Main()
     {
         // Make sure color codes are not produced because we rely on the output in tests
@@ -24,9 +24,6 @@ public static partial class Program
             "false"
         );
 
-        await new CliApplicationBuilder()
-            .AddCommandsFromThisAssembly()
-            .Build()
-            .RunAsync();
+        await new CliApplicationBuilder().AddCommandsFromThisAssembly().Build().RunAsync();
     }
-}
+}

CliFx.Tests/ApplicationSpecs.cs

@@ -11,12 +11,10 @@ namespace CliFx.Tests;
 public class ApplicationSpecs : SpecsBase
 {
     public ApplicationSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Application_can_be_created_with_minimal_configuration()
+    public async Task I_can_create_an_application_with_the_default_configuration()
     {
         // Act
         var app = new CliApplicationBuilder()
@@ -24,24 +22,21 @@ public class ApplicationSpecs : SpecsBase
             .UseConsole(FakeConsole)
             .Build();
 
-        var exitCode = await app.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>()
-        );
+        var exitCode = await app.RunAsync(Array.Empty<string>(), new Dictionary<string, string>());
 
         // Assert
         exitCode.Should().Be(0);
     }
 
     [Fact]
-    public async Task Application_can_be_created_with_a_fully_customized_configuration()
+    public async Task I_can_create_an_application_with_a_custom_configuration()
     {
         // Act
         var app = new CliApplicationBuilder()
             .AddCommand<NoOpCommand>()
             .AddCommandsFrom(typeof(NoOpCommand).Assembly)
-            .AddCommands(new[] {typeof(NoOpCommand)})
-            .AddCommandsFrom(new[] {typeof(NoOpCommand).Assembly})
+            .AddCommands(new[] { typeof(NoOpCommand) })
+            .AddCommandsFrom(new[] { typeof(NoOpCommand).Assembly })
             .AddCommandsFromThisAssembly()
             .AllowDebugMode()
             .AllowPreviewMode()
@@ -53,17 +48,14 @@ public class ApplicationSpecs : SpecsBase
             .UseTypeActivator(Activator.CreateInstance!)
             .Build();
 
-        var exitCode = await app.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>()
-        );
+        var exitCode = await app.RunAsync(Array.Empty<string>(), new Dictionary<string, string>());
 
         // Assert
         exitCode.Should().Be(0);
     }
 
     [Fact]
-    public async Task Application_configuration_fails_if_an_invalid_command_is_registered()
+    public async Task I_can_try_to_create_an_application_and_get_an_error_if_it_has_invalid_commands()
     {
         // Act
         var app = new CliApplicationBuilder()
@@ -71,15 +63,12 @@ public class ApplicationSpecs : SpecsBase
             .UseConsole(FakeConsole)
             .Build();
 
-        var exitCode = await app.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>()
-        );
-
-        var stdErr = FakeConsole.ReadErrorString();
+        var exitCode = await app.RunAsync(Array.Empty<string>(), new Dictionary<string, string>());
 
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("not a valid command");
     }
-}
+}

CliFx.Tests/CancellationSpecs.cs

@@ -1,7 +1,11 @@
 using System;
 using System.Collections.Generic;
+using System.Text;
+using System.Threading;
 using System.Threading.Tasks;
 using CliFx.Tests.Utils;
+using CliFx.Tests.Utils.Extensions;
+using CliWrap;
 using FluentAssertions;
 using Xunit;
 using Xunit.Abstractions;
@@ -11,16 +15,52 @@ namespace CliFx.Tests;
 public class CancellationSpecs : SpecsBase
 {
     public CancellationSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
+        : base(testOutput) { }
+
+    [Fact(Timeout = 15000)]
+    public async Task I_can_configure_the_command_to_listen_to_the_interrupt_signal()
     {
+        // Arrange
+        using var cts = new CancellationTokenSource();
+
+        // We need to send the cancellation request right after the process has registered
+        // a handler for the interrupt signal, otherwise the default handler will trigger
+        // and just kill the process.
+        void HandleStdOut(string line)
+        {
+            if (string.Equals(line, "Started.", StringComparison.OrdinalIgnoreCase))
+                cts.CancelAfter(TimeSpan.FromSeconds(0.2));
+        }
+
+        var stdOutBuffer = new StringBuilder();
+
+        var pipeTarget = PipeTarget.Merge(
+            PipeTarget.ToDelegate(HandleStdOut),
+            PipeTarget.ToStringBuilder(stdOutBuffer)
+        );
+
+        var command = Cli.Wrap(Dummy.Program.FilePath).WithArguments("cancel-test") | pipeTarget;
+
+        // Act & assert
+        await Assert.ThrowsAnyAsync<OperationCanceledException>(
+            async () =>
+                await command.ExecuteAsync(
+                    // Forceful cancellation (not required because we have a timeout)
+                    CancellationToken.None,
+                    // Graceful cancellation
+                    cts.Token
+                )
+        );
+
+        stdOutBuffer.ToString().Trim().Should().ConsistOfLines("Started.", "Cancelled.");
     }
 
     [Fact]
-    public async Task Command_can_receive_a_cancellation_signal_from_the_console()
+    public async Task I_can_configure_the_command_to_listen_to_the_interrupt_signal_when_running_in_isolation()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -29,16 +69,18 @@ public class CancellationSpecs : SpecsBase
                 {
                     try
                     {
+                        console.Output.WriteLine("Started.");
+
                         await Task.Delay(
                             TimeSpan.FromSeconds(3),
                             console.RegisterCancellationHandler()
                         );
 
-                        console.Output.WriteLine("Completed successfully");
+                        console.Output.WriteLine("Completed.");
                     }
                     catch (OperationCanceledException)
                     {
-                        console.Output.WriteLine("Cancelled");
+                        console.Output.WriteLine("Cancelled.");
                         throw;
                     }
                 }
@@ -51,18 +93,18 @@ public class CancellationSpecs : SpecsBase
             .UseConsole(FakeConsole)
             .Build();
 
-        // Act
         FakeConsole.RequestCancellation(TimeSpan.FromSeconds(0.2));
 
+        // Act
         var exitCode = await application.RunAsync(
             Array.Empty<string>(),
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().NotBe(0);
-        stdOut.Trim().Should().Be("Cancelled");
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Trim().Should().ConsistOfLines("Started.", "Cancelled.");
     }
-}
+}

CliFx.Tests/CliFx.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0</TargetFramework>
+    <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
@@ -9,16 +9,18 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.1" />
-    <PackageReference Include="CliWrap" Version="3.6.1" />
-    <PackageReference Include="FluentAssertions" Version="6.11.0" />
-    <PackageReference Include="GitHubActionsTestLogger" Version="2.0.2" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" />
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="7.0.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
-    <PackageReference Include="xunit" Version="2.4.2" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5" PrivateAssets="all" />
-    <PackageReference Include="coverlet.collector" Version="3.2.0" PrivateAssets="all" />
+    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.5" />
+    <PackageReference Include="CliWrap" Version="3.6.4" />
+    <PackageReference Include="coverlet.collector" Version="6.0.0" PrivateAssets="all" />
+    <PackageReference Include="CSharpier.MsBuild" Version="0.26.1" PrivateAssets="all" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="GitHubActionsTestLogger" Version="2.3.3" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.7.0" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="PolyShim" Version="1.8.0" PrivateAssets="all" />
+    <PackageReference Include="xunit" Version="2.6.1" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.5.3" PrivateAssets="all" />
   </ItemGroup>
 
   <ItemGroup>

CliFx.Tests/ConsoleSpecs.cs

@@ -17,22 +17,16 @@ namespace CliFx.Tests;
 public class ConsoleSpecs : SpecsBase
 {
     public ConsoleSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact(Timeout = 15000)]
-    public async Task Real_console_maps_directly_to_system_console()
+    public async Task I_can_run_the_application_with_the_default_console_implementation_to_interact_with_the_system_console()
     {
-        // Can't verify our own console output, so using an
-        // external process for this test.
+        // Can't verify our own console output, so using an external process for this test
 
         // Arrange
-        var command = "Hello world" | Cli.Wrap("dotnet")
-            .WithArguments(a => a
-                .Add(Dummy.Program.Location)
-                .Add("console-test")
-            );
+        var command =
+            "Hello world" | Cli.Wrap(Dummy.Program.FilePath).WithArguments("console-test");
 
         // Act
         var result = await command.ExecuteBufferedAsync();
@@ -43,11 +37,30 @@ public class ConsoleSpecs : SpecsBase
     }
 
     [Fact]
-    public async Task Fake_console_does_not_leak_to_system_console()
+    public void I_can_run_the_application_on_a_system_with_a_custom_console_encoding_and_not_get_corrupted_output()
+    {
+        // Arrange
+        using var buffer = new MemoryStream();
+        using var consoleWriter = new ConsoleWriter(FakeConsole, buffer, Encoding.UTF8);
+
+        // Act
+        consoleWriter.Write("Hello world");
+        consoleWriter.Flush();
+
+        // Assert
+        var outputBytes = buffer.ToArray();
+        outputBytes.Should().NotContain(Encoding.UTF8.GetPreamble());
+
+        var output = consoleWriter.Encoding.GetString(outputBytes);
+        output.Should().Be("Hello world");
+    }
+
+    [Fact]
+    public async Task I_can_run_the_application_with_the_fake_console_implementation_to_isolate_console_interactions()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -104,11 +117,11 @@ public class ConsoleSpecs : SpecsBase
     }
 
     [Fact]
-    public async Task Fake_console_can_be_used_with_an_in_memory_backing_store()
+    public async Task I_can_run_the_application_with_the_fake_console_implementation_and_simulate_stream_interactions()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -138,21 +151,22 @@ public class ConsoleSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("Hello world");
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Trim().Should().Be("Hello world");
     }
 
     [Fact]
-    public async Task Fake_console_can_read_key_presses()
+    public async Task I_can_run_the_application_with_the_fake_console_implementation_and_simulate_key_presses()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -184,31 +198,10 @@ public class ConsoleSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Trim().Should().ConsistOfLines(
-            "D0",
-            "A",
-            "Backspace"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Trim().Should().ConsistOfLines("D0", "A", "Backspace");
     }
-
-    [Fact]
-    public void Console_does_not_emit_preamble_when_used_with_encoding_that_has_it()
-    {
-        // Arrange
-        using var buffer = new MemoryStream();
-        using var consoleWriter = new ConsoleWriter(FakeConsole, buffer, Encoding.UTF8);
-
-        // Act
-        consoleWriter.Write("Hello world");
-        consoleWriter.Flush();
-
-        var output = consoleWriter.Encoding.GetString(buffer.ToArray());
-
-        // Assert
-        output.Should().Be("Hello world");
-    }
-}
+}

CliFx.Tests/ConversionSpecs.cs

@@ -11,22 +11,20 @@ namespace CliFx.Tests;
 public class ConversionSpecs : SpecsBase
 {
     public ConversionSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_string()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_string_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -44,29 +42,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "xyz"},
+            new[] { "-f", "xyz" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("xyz");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_an_object()
+    public async Task I_can_bind_a_parameter_or_an_option_to_an_object_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public object Foo { get; set; }
+                public object? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -84,37 +82,41 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "xyz"},
+            new[] { "-f", "xyz" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("xyz");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_boolean()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_boolean_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public bool Foo { get; set; }
+                public bool Foo { get; init; }
 
                 [CommandOption('b')]
-                public bool Bar { get; set; }
+                public bool Bar { get; init; }
+
+                [CommandOption('c')]
+                public bool Baz { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
                     console.Output.WriteLine("Foo = " + Foo);
                     console.Output.WriteLine("Bar = " + Bar);
+                    console.Output.WriteLine("Baz = " + Baz);
 
                     return default;
                 }
@@ -129,32 +131,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "true", "-b", "false"},
+            new[] { "-f", "true", "-b", "false", "-c" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = True",
-            "Bar = False"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = True", "Bar = False", "Baz = True");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_boolean_with_implicit_value()
+    public async Task I_can_bind_a_parameter_or_an_option_to_an_integer_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public bool Foo { get; set; }
+                public int Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -172,69 +171,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f"},
+            new[] { "-f", "32" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Trim().Should().Be("True");
-    }
-
-    [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_an_integer()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption('f')]
-                public int Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console)
-                {
-                    console.Output.WriteLine(Foo);
-                    return default;
-                }
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"-f", "32"},
-            new Dictionary<string, string>()
-        );
 
         var stdOut = FakeConsole.ReadOutputString();
-
-        // Assert
-        exitCode.Should().Be(0);
         stdOut.Trim().Should().Be("32");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_double()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_double_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public double Foo { get; set; }
+                public double Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -252,29 +211,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "32.14"},
+            new[] { "-f", "32.14" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("32.14");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_DateTimeOffset()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_DateTimeOffset_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public DateTimeOffset Foo { get; set; }
+                public DateTimeOffset Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -292,29 +251,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "1995-04-28Z"},
+            new[] { "-f", "1995-04-28Z" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("1995-04-28 00:00:00Z");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_TimeSpan()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_TimeSpan_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public TimeSpan Foo { get; set; }
+                public TimeSpan Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -332,23 +291,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "12:34:56"},
+            new[] { "-f", "12:34:56" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("12:34:56");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_an_enum()
+    public async Task I_can_bind_a_parameter_or_an_option_to_an_enum_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public enum CustomEnum { One = 1, Two = 2, Three = 3 }
 
@@ -356,7 +315,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomEnum Foo { get; set; }
+                public CustomEnum Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -374,32 +333,32 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "two"},
+            new[] { "-f", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("2");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_nullable_integer()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_nullable_integer_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public int? Foo { get; set; }
+                public int? Foo { get; init; }
 
                 [CommandOption('b')]
-                public int? Bar { get; set; }
+                public int? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -419,26 +378,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-b", "123"},
+            new[] { "-b", "123" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = ",
-            "Bar = 123"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = ", "Bar = 123");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_nullable_enum()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_nullable_enum_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public enum CustomEnum { One = 1, Two = 2, Three = 3 }
 
@@ -446,10 +402,10 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomEnum? Foo { get; set; }
+                public CustomEnum? Foo { get; init; }
 
                 [CommandOption('b')]
-                public CustomEnum? Bar { get; set; }
+                public CustomEnum? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -469,26 +425,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-b", "two"},
+            new[] { "-b", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = ",
-            "Bar = 2"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = ", "Bar = 2");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_type_that_has_a_constructor_accepting_a_string()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_string_constructable_object_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public class CustomType
             {
@@ -501,7 +454,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomType Foo { get; set; }
+                public CustomType? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -519,23 +472,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "xyz"},
+            new[] { "-f", "xyz" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("xyz");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_type_that_has_a_static_parse_method()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_string_parsable_object_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public class CustomTypeA
             {
@@ -561,10 +514,10 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomTypeA Foo { get; set; }
+                public CustomTypeA? Foo { get; init; }
 
                 [CommandOption('b')]
-                public CustomTypeB Bar { get; set; }
+                public CustomTypeB? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -584,26 +537,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "hello", "-b", "world"},
+            new[] { "-f", "hello", "-b", "world" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = hello",
-            "Bar = world"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = hello", "Bar = world");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_using_a_custom_converter()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_property_with_a_custom_converter()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public class CustomConverter : BindingConverter<int>
             {
@@ -615,7 +565,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f', Converter = typeof(CustomConverter))]
-                public int Foo { get; set; }
+                public int Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -633,29 +583,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "hello world"},
+            new[] { "-f", "hello world" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("11");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_an_array_of_strings()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_string_array_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public string[] Foo { get; set; }
+                public string[]? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -675,33 +625,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "two", "three"},
+            new[] { "-f", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_read_only_list_of_strings()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_read_only_list_of_strings_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -721,33 +667,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "two", "three"},
+            new[] { "-f", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_a_list_of_strings()
+    public async Task I_can_bind_a_parameter_or_an_option_to_a_string_list_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public List<string> Foo { get; set; }
+                public List<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -767,33 +709,29 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "two", "three"},
+            new[] { "-f", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_can_be_converted_to_an_array_of_integers()
+    public async Task I_can_bind_a_parameter_or_an_option_to_an_integer_array_property()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public int[] Foo { get; set; }
+                public int[]? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -813,33 +751,33 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "1", "13", "27"},
+            new[] { "-f", "1", "13", "27" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "1",
-            "13",
-            "27"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("1", "13", "27");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_conversion_fails_if_the_value_cannot_be_converted_to_the_target_type()
+    public async Task I_can_try_to_bind_a_parameter_or_an_option_to_a_property_and_get_an_error_if_it_is_of_an_unsupported_type()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
+            public class CustomType
+            {
+            }
+
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public int Foo { get; set; }
+                public CustomType? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -853,61 +791,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "12.34"},
+            new[] { "-f", "xyz" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
-        stdErr.Should().NotBeNullOrWhiteSpace();
-    }
-
-    [Fact]
-    public async Task Parameter_or_option_value_conversion_fails_if_the_target_type_is_not_supported()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            public class CustomType {}
-
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption('f')]
-                public CustomType Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"-f", "xyz"},
-            new Dictionary<string, string>()
-        );
 
         var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
         stdErr.Should().Contain("has an unsupported underlying property type");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_conversion_fails_if_the_target_non_scalar_type_is_not_supported()
+    public async Task I_can_try_to_bind_a_parameter_or_an_option_to_a_non_scalar_property_and_get_an_error_if_it_is_of_an_unsupported_type()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public class CustomType : IEnumerable<object>
             {
@@ -920,7 +820,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomType Foo { get; set; }
+                public CustomType? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -934,23 +834,59 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "two"},
+            new[] { "-f", "one", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("has an unsupported underlying property type");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_conversion_fails_if_one_of_the_validators_fail()
+    public async Task I_can_try_to_bind_a_parameter_or_an_option_to_a_property_and_get_an_error_if_the_user_provides_an_invalid_value()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                [CommandOption('f')]
+                public int Foo { get; init; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """
+        );
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            new[] { "-f", "12.34" },
+            new Dictionary<string, string>()
+        );
+
+        // Assert
+        exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().NotBeNullOrWhiteSpace();
+    }
+
+    [Fact]
+    public async Task I_can_try_to_bind_a_parameter_or_an_option_to_a_property_and_get_an_error_if_a_custom_validator_fails()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // lang=csharp
             """
             public class ValidatorA : BindingValidator<int>
             {
@@ -966,7 +902,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f', Validators = new[] {typeof(ValidatorA), typeof(ValidatorB)})]
-                public int Foo { get; set; }
+                public int Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -980,23 +916,23 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "12"},
+            new[] { "-f", "12" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Hello world");
     }
 
     [Fact]
-    public async Task Parameter_or_option_value_conversion_fails_if_the_static_parse_method_throws()
+    public async Task I_can_try_to_bind_a_parameter_or_an_option_to_a_string_parsable_property_and_get_an_error_if_the_parsing_fails()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public class CustomType
             {
@@ -1011,7 +947,7 @@ public class ConversionSpecs : SpecsBase
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public CustomType Foo { get; set; }
+                public CustomType? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -1025,14 +961,14 @@ public class ConversionSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "bar"},
+            new[] { "-f", "bar" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Hello world");
     }
-}
+}

CliFx.Tests/DirectivesSpecs.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using CliFx.Tests.Utils;
@@ -15,12 +14,10 @@ namespace CliFx.Tests;
 public class DirectivesSpecs : SpecsBase
 {
     public DirectivesSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact(Timeout = 15000)]
-    public async Task Debug_directive_can_be_specified_to_interrupt_execution_until_a_debugger_is_attached()
+    public async Task I_can_use_the_debug_directive_to_make_the_application_wait_for_the_debugger_to_attach()
     {
         // Arrange
         using var cts = new CancellationTokenSource();
@@ -29,15 +26,11 @@ public class DirectivesSpecs : SpecsBase
         void HandleStdOut(string line)
         {
             // Kill the process once it writes the output we expect
-            if (line.Contains("Attach debugger to", StringComparison.OrdinalIgnoreCase))
+            if (line.Contains("Attach the debugger to", StringComparison.OrdinalIgnoreCase))
                 cts.Cancel();
         }
 
-        var command = Cli.Wrap("dotnet")
-            .WithArguments(a => a
-                .Add(Dummy.Program.Location)
-                .Add("[debug]")
-            ) | HandleStdOut;
+        var command = Cli.Wrap(Dummy.Program.FilePath).WithArguments("[debug]") | HandleStdOut;
 
         // Act & assert
         try
@@ -51,11 +44,11 @@ public class DirectivesSpecs : SpecsBase
     }
 
     [Fact]
-    public async Task Preview_directive_can_be_specified_to_print_command_input()
+    public async Task I_can_use_the_preview_directive_to_make_the_application_print_the_parsed_command_input()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command("cmd")]
             public class Command : ICommand
@@ -73,22 +66,29 @@ public class DirectivesSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"[preview]", "cmd", "param", "-abc", "--option", "foo"},
-            new Dictionary<string, string>
-            {
-                ["ENV_QOP"] = "hello",
-                ["ENV_KIL"] = "world"
-            }
+            new[] { "[preview]", "cmd", "param", "-abc", "--option", "foo" },
+            new Dictionary<string, string> { ["ENV_QOP"] = "hello", ["ENV_KIL"] = "world" }
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ContainAllInOrder(
-            "cmd", "<param>", "[-a]", "[-b]", "[-c]", "[--option \"foo\"]",
-            "ENV_QOP", "=", "\"hello\"",
-            "ENV_KIL", "=", "\"world\""
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut
+            .Should()
+            .ContainAllInOrder(
+                "cmd",
+                "<param>",
+                "[-a]",
+                "[-b]",
+                "[-c]",
+                "[--option \"foo\"]",
+                "ENV_QOP",
+                "=",
+                "\"hello\"",
+                "ENV_KIL",
+                "=",
+                "\"world\""
+            );
     }
-}
+}

CliFx.Tests/EnvironmentSpecs.cs

@@ -15,26 +15,29 @@ namespace CliFx.Tests;
 public class EnvironmentSpecs : SpecsBase
 {
     public EnvironmentSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Option_can_fall_back_to_an_environment_variable()
+    public async Task I_can_configure_an_option_to_fall_back_to_an_environment_variable_if_the_user_does_not_provide_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
-                [CommandOption("foo", IsRequired = true, EnvironmentVariable = "ENV_FOO")]
-                public string Foo { get; set; }
+                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
+                public string? Foo { get; init; }
+
+                [CommandOption("bar", EnvironmentVariable = "ENV_BAR")]
+                public string? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
                     console.Output.WriteLine(Foo);
+                    console.Output.WriteLine(Bar);
+
                     return default;
                 }
             }
@@ -48,75 +51,29 @@ public class EnvironmentSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>
-            {
-                ["ENV_FOO"] = "bar"
-            }
+            new[] { "--foo", "42" },
+            new Dictionary<string, string> { ["ENV_FOO"] = "100", ["ENV_BAR"] = "200" }
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Trim().Should().Be("bar");
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Trim().Should().ConsistOfLines("42", "200");
     }
 
     [Fact]
-    public async Task Option_does_not_fall_back_to_an_environment_variable_if_a_value_is_provided_through_arguments()
+    public async Task I_can_configure_an_option_bound_to_a_non_scalar_property_to_fall_back_to_an_environment_variable_if_the_user_does_not_provide_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
-                public string Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console)
-                {
-                    console.Output.WriteLine(Foo);
-                    return default;
-                }
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"--foo", "baz"},
-            new Dictionary<string, string>
-            {
-                ["ENV_FOO"] = "bar"
-            }
-        );
-
-        var stdOut = FakeConsole.ReadOutputString();
-
-        // Assert
-        exitCode.Should().Be(0);
-        stdOut.Trim().Should().Be("baz");
-    }
-
-    [Fact]
-    public async Task Option_of_non_scalar_type_can_receive_multiple_values_from_an_environment_variable()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -137,34 +94,28 @@ public class EnvironmentSpecs : SpecsBase
         // Act
         var exitCode = await application.RunAsync(
             Array.Empty<string>(),
-            new Dictionary<string, string>
-            {
-                ["ENV_FOO"] = $"bar{Path.PathSeparator}baz"
-            }
+            new Dictionary<string, string> { ["ENV_FOO"] = $"bar{Path.PathSeparator}baz" }
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "bar",
-            "baz"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("bar", "baz");
     }
 
     [Fact]
-    public async Task Option_of_scalar_type_always_receives_a_single_value_from_an_environment_variable()
+    public async Task I_can_configure_an_option_bound_to_a_scalar_property_to_fall_back_to_an_environment_variable_while_ignoring_path_separators()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -183,79 +134,26 @@ public class EnvironmentSpecs : SpecsBase
         // Act
         var exitCode = await application.RunAsync(
             Array.Empty<string>(),
-            new Dictionary<string, string>
-            {
-                ["ENV_FOO"] = $"bar{Path.PathSeparator}baz"
-            }
+            new Dictionary<string, string> { ["ENV_FOO"] = $"bar{Path.PathSeparator}baz" }
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be($"bar{Path.PathSeparator}baz");
     }
 
-    [Fact]
-    public async Task Environment_variables_are_matched_case_sensitively()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
-                public string Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console)
-                {
-                    console.Output.WriteLine(Foo);
-                    return default;
-                }
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>
-            {
-                ["ENV_foo"] = "baz",
-                ["ENV_FOO"] = "bar",
-                ["env_FOO"] = "qop"
-            }
-        );
-
-        var stdOut = FakeConsole.ReadOutputString();
-
-        // Assert
-        exitCode.Should().Be(0);
-        stdOut.Trim().Should().Be("bar");
-    }
-
     [Fact(Timeout = 15000)]
-    public async Task Environment_variables_are_extracted_automatically()
+    public async Task I_can_run_the_application_and_it_will_resolve_all_required_environment_variables_automatically()
     {
         // Ensures that the environment variables are properly obtained from
         // System.Environment when they are not provided explicitly to CliApplication.
 
         // Arrange
-        var command = Cli.Wrap("dotnet")
-            .WithArguments(a => a
-                .Add(Dummy.Program.Location)
-                .Add("env-test")
-            )
-            .WithEnvironmentVariables(e => e
-                .Set("ENV_TARGET", "Mars")
-            );
+        var command = Cli.Wrap(Dummy.Program.FilePath)
+            .WithArguments("env-test")
+            .WithEnvironmentVariables(e => e.Set("ENV_TARGET", "Mars"));
 
         // Act
         var result = await command.ExecuteBufferedAsync();
@@ -263,4 +161,4 @@ public class EnvironmentSpecs : SpecsBase
         // Assert
         result.StandardOutput.Trim().Should().Be("Hello Mars!");
     }
-}
+}

CliFx.Tests/ErrorReportingSpecs.cs

@@ -12,16 +12,14 @@ namespace CliFx.Tests;
 public class ErrorReportingSpecs : SpecsBase
 {
     public ErrorReportingSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Command_can_throw_an_exception_which_exits_with_a_stacktrace()
+    public async Task I_can_throw_an_exception_in_a_command_to_report_an_error_with_a_stacktrace()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -43,24 +41,24 @@ public class ErrorReportingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Should().BeEmpty();
-        stdErr.Should().ContainAllInOrder(
-            "System.Exception", "Something went wrong",
-            "at", "CliFx."
-        );
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr
+            .Should()
+            .ContainAllInOrder("System.Exception", "Something went wrong", "at", "CliFx.");
     }
 
     [Fact]
-    public async Task Command_can_throw_an_exception_with_an_inner_exception_which_exits_with_a_stacktrace()
+    public async Task I_can_throw_an_exception_with_an_inner_exception_in_a_command_to_report_an_error_with_a_stacktrace()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -82,25 +80,31 @@ public class ErrorReportingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Should().BeEmpty();
-        stdErr.Should().ContainAllInOrder(
-            "System.Exception", "Something went wrong",
-            "System.Exception", "Another exception",
-            "at", "CliFx."
-        );
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr
+            .Should()
+            .ContainAllInOrder(
+                "System.Exception",
+                "Something went wrong",
+                "System.Exception",
+                "Another exception",
+                "at",
+                "CliFx."
+            );
     }
 
     [Fact]
-    public async Task Command_can_throw_a_special_exception_which_exits_with_specified_code_and_message()
+    public async Task I_can_throw_an_exception_in_a_command_to_report_an_error_and_exit_with_the_specified_code()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -122,21 +126,22 @@ public class ErrorReportingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().Be(69);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Should().BeEmpty();
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Trim().Should().Be("Something went wrong");
     }
 
     [Fact]
-    public async Task Command_can_throw_a_special_exception_without_message_which_exits_with_a_stacktrace()
+    public async Task I_can_throw_an_exception_without_a_message_in_a_command_to_report_an_error_with_a_stacktrace()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -158,24 +163,22 @@ public class ErrorReportingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().Be(69);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Should().BeEmpty();
-        stdErr.Should().ContainAllInOrder(
-            "CliFx.Exceptions.CommandException",
-            "at", "CliFx."
-        );
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().ContainAllInOrder("CliFx.Exceptions.CommandException", "at", "CliFx.");
     }
 
     [Fact]
-    public async Task Command_can_throw_a_special_exception_which_prints_help_text_before_exiting()
+    public async Task I_can_throw_an_exception_in_a_command_to_report_an_error_and_print_the_help_text()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -198,12 +201,13 @@ public class ErrorReportingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().Be(69);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Should().Contain("This will be in help text");
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Trim().Should().Be("Something went wrong");
     }
-}
+}

CliFx.Tests/OptionBindingSpecs.cs

@@ -12,22 +12,20 @@ namespace CliFx.Tests;
 public class OptionBindingSpecs : SpecsBase
 {
     public OptionBindingSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Option_is_bound_from_an_argument_matching_its_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_value_from_the_corresponding_argument_by_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public bool Foo { get; set; }
+                public bool Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -45,29 +43,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo"},
+            new[] { "--foo" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("True");
     }
 
     [Fact]
-    public async Task Option_is_bound_from_an_argument_matching_its_short_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_value_from_the_corresponding_argument_by_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public bool Foo { get; set; }
+                public bool Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -84,33 +82,30 @@ public class OptionBindingSpecs : SpecsBase
             .Build();
 
         // Act
-        var exitCode = await application.RunAsync(
-            new[] {"-f"},
-            new Dictionary<string, string>()
-        );
-
-        var stdOut = FakeConsole.ReadOutputString();
+        var exitCode = await application.RunAsync(new[] { "-f" }, new Dictionary<string, string>());
 
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("True");
     }
 
     [Fact]
-    public async Task Option_is_bound_from_a_set_of_arguments_matching_its_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_value_from_the_corresponding_argument_set_by_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 [CommandOption("bar")]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -130,35 +125,32 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "--bar", "two"},
+            new[] { "--foo", "one", "--bar", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = one",
-            "Bar = two"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = one", "Bar = two");
     }
 
     [Fact]
-    public async Task Option_is_bound_from_a_set_of_arguments_matching_its_short_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_value_from_the_corresponding_argument_set_by_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 [CommandOption('b')]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -178,35 +170,32 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "-b", "two"},
+            new[] { "-f", "one", "-b", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = one",
-            "Bar = two"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = one", "Bar = two");
     }
 
     [Fact]
-    public async Task Option_is_bound_from_a_stack_of_arguments_matching_its_short_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_value_from_the_corresponding_argument_stack_by_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 [CommandOption('b')]
-                public string Bar { get; set; }
+                public string? Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -226,32 +215,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-fb", "value"},
+            new[] { "-fb", "value" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = ",
-            "Bar = value"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = ", "Bar = value");
     }
 
     [Fact]
-    public async Task Option_of_non_scalar_type_is_bound_from_a_set_of_arguments_matching_its_name()
+    public async Task I_can_bind_an_option_to_a_non_scalar_property_and_get_the_values_from_the_corresponding_arguments_by_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("Foo")]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -271,33 +257,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "two", "three"},
+            new[] { "--foo", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Option_of_non_scalar_type_is_bound_from_a_set_of_arguments_matching_its_short_name()
+    public async Task I_can_bind_an_option_to_a_non_scalar_property_and_get_the_values_from_the_corresponding_arguments_by_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -317,33 +299,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "two", "three"},
+            new[] { "-f", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Option_of_non_scalar_type_is_bound_from_multiple_sets_of_arguments_matching_its_name()
+    public async Task I_can_bind_an_option_to_a_non_scalar_property_and_get_the_values_from_the_corresponding_argument_sets_by_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -363,33 +341,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "--foo", "two", "--foo", "three"},
+            new[] { "--foo", "one", "--foo", "two", "--foo", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Option_of_non_scalar_type_is_bound_from_multiple_sets_of_arguments_matching_its_short_name()
+    public async Task I_can_bind_an_option_to_a_non_scalar_property_and_get_the_values_from_the_corresponding_argument_sets_by_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption('f')]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -409,33 +383,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"-f", "one", "-f", "two", "-f", "three"},
+            new[] { "-f", "one", "-f", "two", "-f", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Option_of_non_scalar_type_is_bound_from_multiple_sets_of_arguments_matching_its_name_or_short_name()
+    public async Task I_can_bind_an_option_to_a_non_scalar_property_and_get_the_values_from_the_corresponding_argument_sets_by_name_or_short_name()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo", 'f')]
-                public IReadOnlyList<string> Foo { get; set; }
+                public IReadOnlyList<string>? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -455,36 +425,32 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "-f", "two", "--foo", "three"},
+            new[] { "--foo", "one", "-f", "two", "--foo", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "one",
-            "two",
-            "three"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("one", "two", "three");
     }
 
     [Fact]
-    public async Task Option_is_not_bound_if_there_are_no_arguments_matching_its_name_or_short_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_no_value_if_the_user_does_not_provide_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 [CommandOption("bar")]
-                public string Bar { get; set; } = "hello";
+                public string? Bar { get; init; } = "hello";
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -504,26 +470,23 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one"},
+            new[] { "--foo", "one" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = one",
-            "Bar = hello"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = one", "Bar = hello");
     }
 
     [Fact]
-    public async Task Option_binding_supports_multiple_inheritance_through_default_interface_members()
+    public async Task I_can_bind_an_option_to_a_property_through_multiple_inheritance()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             public static class SharedContext
             {
@@ -538,7 +501,7 @@ public class OptionBindingSpecs : SpecsBase
                 public int Foo
                 {
                     get => SharedContext.Foo;
-                    set => SharedContext.Foo = value;
+                    init => SharedContext.Foo = value;
                 }
             }
 
@@ -548,20 +511,20 @@ public class OptionBindingSpecs : SpecsBase
                 public bool Bar
                 {
                     get => SharedContext.Bar;
-                    set => SharedContext.Bar = value;
+                    init => SharedContext.Bar = value;
                 }
             }
 
             public interface IHasBaz : ICommand
             {
-                public string Baz { get; set; }
+                public string? Baz { get; init; }
             }
 
             [Command]
             public class Command : IHasFoo, IHasBar, IHasBaz
             {
                 [CommandOption("baz")]
-                public string Baz { get; set; }
+                public string? Baz { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -581,38 +544,31 @@ public class OptionBindingSpecs : SpecsBase
             .Build();
 
         // Act
-        var exitCode = await application.RunAsync(
-            new[] { "--foo", "42", "--bar", "--baz", "xyz" }
-        );
-
-        var stdOut = FakeConsole.ReadOutputString();
+        var exitCode = await application.RunAsync(new[] { "--foo", "42", "--bar", "--baz", "xyz" });
 
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = 42",
-            "Bar = True",
-            "Baz = xyz"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = 42", "Bar = True", "Baz = xyz");
     }
 
     [Fact]
-    public async Task Option_binding_does_not_consider_a_negative_number_as_an_option_name_or_short_name()
+    public async Task I_can_bind_an_option_to_a_property_and_get_the_correct_value_if_the_user_provides_an_argument_containing_a_negative_number()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
                     console.Output.WriteLine(Foo);
-
                     return default;
                 }
             }
@@ -626,29 +582,29 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "-13"},
+            new[] { "--foo", "-13" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("-13");
     }
 
     [Fact]
-    public async Task Option_binding_fails_if_a_required_option_has_not_been_provided()
+    public async Task I_can_try_to_bind_a_required_option_to_a_property_and_get_an_error_if_the_user_does_not_provide_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
-                [CommandOption("foo", IsRequired = true)]
-                public string Foo { get; set; }
+                [CommandOption("foo")]
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -666,97 +622,25 @@ public class OptionBindingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Missing required option(s)");
     }
 
     [Fact]
-    public async Task Option_binding_fails_if_a_required_option_has_been_provided_with_an_empty_value()
+    public async Task I_can_try_to_bind_a_required_option_to_a_property_and_get_an_error_if_the_user_provides_an_empty_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption("foo", IsRequired = true)]
-                public string Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"--foo"},
-            new Dictionary<string, string>()
-        );
-
-        var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
-        stdErr.Should().Contain("Missing required option(s)");
-    }
-
-    [Fact]
-    public async Task Option_binding_fails_if_a_required_option_of_non_scalar_type_has_not_been_provided_with_at_least_one_value()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption("foo", IsRequired = true)]
-                public IReadOnlyList<string> Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"--foo"},
-            new Dictionary<string, string>()
-        );
-
-        var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
-        stdErr.Should().Contain("Missing required option(s)");
-    }
-
-    [Fact]
-    public async Task Option_binding_fails_if_one_of_the_provided_option_names_is_not_recognized()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -770,29 +654,101 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "--bar", "two"},
+            new[] { "--foo" },
             new Dictionary<string, string>()
         );
 
+        // Assert
+        exitCode.Should().NotBe(0);
+
         var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().Contain("Missing required option(s)");
+    }
+
+    [Fact]
+    public async Task I_can_try_to_bind_an_option_to_a_non_scalar_property_and_get_an_error_if_the_user_does_not_provide_at_least_one_corresponding_argument()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // lang=csharp
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                [CommandOption("foo")]
+                public required IReadOnlyList<string> Foo { get; init; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """
+        );
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            new[] { "--foo" },
+            new Dictionary<string, string>()
+        );
 
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().Contain("Missing required option(s)");
+    }
+
+    [Fact]
+    public async Task I_can_try_to_bind_options_and_get_an_error_if_the_user_provides_unrecognized_arguments()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // lang=csharp
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                [CommandOption("foo")]
+                public string? Foo { get; init; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """
+        );
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            new[] { "--foo", "one", "--bar", "two" },
+            new Dictionary<string, string>()
+        );
+
+        // Assert
+        exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Unrecognized option(s)");
     }
 
     [Fact]
-    public async Task Option_binding_fails_if_an_option_of_scalar_type_has_been_provided_with_multiple_values()
+    public async Task I_can_try_to_bind_an_option_to_a_scalar_property_and_get_an_error_if_the_user_provides_too_many_arguments()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandOption("foo")]
-                public string Foo { get; set; }
+                public string? Foo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -806,50 +762,14 @@ public class OptionBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"--foo", "one", "two", "three"},
+            new[] { "--foo", "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("expects a single argument, but provided with multiple");
     }
-
-    [Fact]
-    public async Task Option_binding_fails_if_a_required_property_option_has_not_been_provided()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandOption("foo")]
-                public required string Foo { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            Array.Empty<string>(),
-            new Dictionary<string, string>()
-        );
-
-        var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
-        stdErr.Should().Contain("Missing required option(s)");
-    }
-}
+}

CliFx.Tests/ParameterBindingSpecs.cs

@@ -11,25 +11,23 @@ namespace CliFx.Tests;
 public class ParameterBindingSpecs : SpecsBase
 {
     public ParameterBindingSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Parameter_is_bound_from_an_argument_matching_its_order()
+    public async Task I_can_bind_a_parameter_to_a_property_and_get_the_value_from_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 [CommandParameter(1)]
-                public string Bar { get; set; }
+                public required string Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -49,41 +47,38 @@ public class ParameterBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"one", "two"},
+            new[] { "one", "two" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = one",
-            "Bar = two"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = one", "Bar = two");
     }
 
     [Fact]
-    public async Task Parameter_of_non_scalar_type_is_bound_from_remaining_non_option_arguments()
+    public async Task I_can_bind_a_parameter_to_a_non_scalar_property_and_get_values_from_the_remaining_non_option_arguments()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 [CommandParameter(1)]
-                public string Bar { get; set; }
+                public required string Bar { get; init; }
 
                 [CommandParameter(2)]
-                public IReadOnlyList<string> Baz { get; set; }
+                public required IReadOnlyList<string> Baz { get; init; }
 
                 [CommandOption("boo")]
-                public string Boo { get; set; }
+                public string? Boo { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -106,38 +101,112 @@ public class ParameterBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"one", "two", "three", "four", "five", "--boo", "xxx"},
+            new[] { "one", "two", "three", "four", "five", "--boo", "xxx" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = one",
-            "Bar = two",
-            "Baz = three",
-            "Baz = four",
-            "Baz = five"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut
+            .Should()
+            .ConsistOfLines("Foo = one", "Bar = two", "Baz = three", "Baz = four", "Baz = five");
     }
 
     [Fact]
-    public async Task Parameter_is_not_bound_if_there_are_no_arguments_matching_its_order()
+    public async Task I_can_try_to_bind_a_parameter_to_a_property_and_get_an_error_if_the_user_does_not_provide_the_corresponding_argument()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
+
+                [CommandParameter(1)]
+                public required string Bar { get; init; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """
+        );
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            new[] { "one" },
+            new Dictionary<string, string>()
+        );
+
+        // Assert
+        exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().Contain("Missing required parameter(s)");
+    }
+
+    [Fact]
+    public async Task I_can_try_to_bind_a_parameter_to_a_non_scalar_property_and_get_an_error_if_the_user_does_not_provide_at_least_one_corresponding_argument()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // lang=csharp
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                [CommandParameter(0)]
+                public required string Foo { get; init; }
+
+                [CommandParameter(1)]
+                public required IReadOnlyList<string> Bar { get; init; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """
+        );
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            new[] { "one" },
+            new Dictionary<string, string>()
+        );
+
+        // Assert
+        exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
+        stdErr.Should().Contain("Missing required parameter(s)");
+    }
+
+    [Fact]
+    public async Task I_can_bind_a_non_required_parameter_to_a_property_and_get_no_value_if_the_user_does_not_provide_the_corresponding_argument()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // lang=csharp
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                [CommandParameter(0)]
+                public required string Foo { get; init; }
 
                 [CommandParameter(1, IsRequired = false)]
-                public string Bar { get; set; } = "xyz";
+                public string? Bar { get; init; } = "xyz";
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
@@ -157,35 +226,32 @@ public class ParameterBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"abc"},
+            new[] { "abc" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Should().ConsistOfLines(
-            "Foo = abc",
-            "Bar = xyz"
-        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+        stdOut.Should().ConsistOfLines("Foo = abc", "Bar = xyz");
     }
 
     [Fact]
-    public async Task Parameter_binding_fails_if_a_required_parameter_has_not_been_provided()
+    public async Task I_can_try_to_bind_parameters_and_get_an_error_if_the_user_provides_too_many_arguments()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
             {
                 [CommandParameter(0)]
-                public string Foo { get; set; }
+                public required string Foo { get; init; }
 
                 [CommandParameter(1)]
-                public string Bar { get; set; }
+                public required string Bar { get; init; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
@@ -199,92 +265,14 @@ public class ParameterBindingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"one"},
+            new[] { "one", "two", "three" },
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
-        stdErr.Should().Contain("Missing required parameter(s)");
-    }
-
-    [Fact]
-    public async Task Parameter_binding_fails_if_a_parameter_of_non_scalar_type_has_not_been_provided_with_at_least_one_value()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandParameter(0)]
-                public string Foo { get; set; }
-
-                [CommandParameter(1)]
-                public IReadOnlyList<string> Bar { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"one"},
-            new Dictionary<string, string>()
-        );
 
         var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
-        stdErr.Should().Contain("Missing required parameter(s)");
-    }
-
-    [Fact]
-    public async Task Parameter_binding_fails_if_one_of_the_provided_parameters_is_unexpected()
-    {
-        // Arrange
-        var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
-            """
-            [Command]
-            public class Command : ICommand
-            {
-                [CommandParameter(0)]
-                public string Foo { get; set; }
-
-                [CommandParameter(1)]
-                public string Bar { get; set; }
-
-                public ValueTask ExecuteAsync(IConsole console) => default;
-            }
-            """
-        );
-
-        var application = new CliApplicationBuilder()
-            .AddCommand(commandType)
-            .UseConsole(FakeConsole)
-            .Build();
-
-        // Act
-        var exitCode = await application.RunAsync(
-            new[] {"one", "two", "three"},
-            new Dictionary<string, string>()
-        );
-
-        var stdErr = FakeConsole.ReadErrorString();
-
-        // Assert
-        exitCode.Should().NotBe(0);
         stdErr.Should().Contain("Unexpected parameter(s)");
     }
-}
+}

CliFx.Tests/RoutingSpecs.cs

@@ -11,16 +11,14 @@ namespace CliFx.Tests;
 public class RoutingSpecs : SpecsBase
 {
     public RoutingSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Default_command_is_executed_if_provided_arguments_do_not_match_any_named_command()
+    public async Task I_can_configure_a_command_to_be_executed_by_default_when_the_user_does_not_specify_a_command_name()
     {
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class DefaultCommand : ICommand
@@ -65,19 +63,19 @@ public class RoutingSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("default");
     }
 
     [Fact]
-    public async Task Specific_named_command_is_executed_if_provided_arguments_match_its_name()
+    public async Task I_can_configure_a_command_to_be_executed_when_the_user_specifies_its_name()
     {
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class DefaultCommand : ICommand
@@ -118,23 +116,23 @@ public class RoutingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"cmd"},
+            new[] { "cmd" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("cmd");
     }
 
     [Fact]
-    public async Task Specific_named_child_command_is_executed_if_provided_arguments_match_its_name()
+    public async Task I_can_configure_a_nested_command_to_be_executed_when_the_user_specifies_its_name()
     {
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class DefaultCommand : ICommand
@@ -175,14 +173,14 @@ public class RoutingSpecs : SpecsBase
 
         // Act
         var exitCode = await application.RunAsync(
-            new[] {"cmd", "child"},
+            new[] { "cmd", "child" },
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("cmd child");
     }
-}
+}

CliFx.Tests/SpecsBase.cs

@@ -11,12 +11,11 @@ public abstract class SpecsBase : IDisposable
 
     public FakeInMemoryConsole FakeConsole { get; } = new();
 
-    protected SpecsBase(ITestOutputHelper testOutput) =>
-        TestOutput = testOutput;
+    protected SpecsBase(ITestOutputHelper testOutput) => TestOutput = testOutput;
 
     public void Dispose()
     {
         FakeConsole.DumpToTestOutput(TestOutput);
         FakeConsole.Dispose();
     }
-}
+}

CliFx.Tests/TypeActivationSpecs.cs

@@ -13,16 +13,14 @@ namespace CliFx.Tests;
 public class TypeActivationSpecs : SpecsBase
 {
     public TypeActivationSpecs(ITestOutputHelper testOutput)
-        : base(testOutput)
-    {
-    }
+        : base(testOutput) { }
 
     [Fact]
-    public async Task Default_type_activator_can_initialize_a_type_if_it_has_a_parameterless_constructor()
+    public async Task I_can_configure_the_application_to_use_the_default_type_activator_to_initialize_types_through_parameterless_constructors()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -48,19 +46,19 @@ public class TypeActivationSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("foo");
     }
 
     [Fact]
-    public async Task Default_type_activator_fails_if_the_type_does_not_have_a_parameterless_constructor()
+    public async Task I_can_try_to_configure_the_application_to_use_the_default_type_activator_and_get_an_error_if_the_requested_type_does_not_have_a_parameterless_constructor()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -84,19 +82,19 @@ public class TypeActivationSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Failed to create an instance of type");
     }
 
     [Fact]
-    public async Task Custom_type_activator_can_initialize_a_type_using_a_given_function()
+    public async Task I_can_configure_the_application_to_use_a_custom_type_activator_to_initialize_types_using_a_delegate()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -126,19 +124,19 @@ public class TypeActivationSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("Hello world");
     }
 
     [Fact]
-    public async Task Custom_type_activator_can_initialize_a_type_using_a_service_provider()
+    public async Task I_can_configure_the_application_to_use_a_custom_type_activator_to_initialize_types_using_a_service_provider()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -156,14 +154,23 @@ public class TypeActivationSpecs : SpecsBase
             """
         );
 
-        var serviceProvider = new ServiceCollection()
-            .AddSingleton(commandType, Activator.CreateInstance(commandType, "Hello world")!)
-            .BuildServiceProvider();
-
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
-            .UseTypeActivator(serviceProvider)
+            .UseTypeActivator(commandTypes =>
+            {
+                var services = new ServiceCollection();
+
+                foreach (var serviceType in commandTypes)
+                {
+                    services.AddSingleton(
+                        serviceType,
+                        Activator.CreateInstance(serviceType, "Hello world")!
+                    );
+                }
+
+                return services.BuildServiceProvider();
+            })
             .Build();
 
         // Act
@@ -172,19 +179,19 @@ public class TypeActivationSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdOut = FakeConsole.ReadOutputString();
-
         // Assert
         exitCode.Should().Be(0);
+
+        var stdOut = FakeConsole.ReadOutputString();
         stdOut.Trim().Should().Be("Hello world");
     }
 
     [Fact]
-    public async Task Custom_type_activator_fails_if_the_underlying_function_returns_null()
+    public async Task I_can_try_to_configure_the_application_to_use_a_custom_type_activator_and_get_an_error_if_the_requested_type_cannot_be_initialized()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
-            // language=cs
+            // lang=csharp
             """
             [Command]
             public class Command : ICommand
@@ -201,7 +208,7 @@ public class TypeActivationSpecs : SpecsBase
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
-            .UseTypeActivator(_ => null!)
+            .UseTypeActivator((Type _) => null!)
             .Build();
 
         // Act
@@ -210,10 +217,10 @@ public class TypeActivationSpecs : SpecsBase
             new Dictionary<string, string>()
         );
 
-        var stdErr = FakeConsole.ReadErrorString();
-
         // Assert
         exitCode.Should().NotBe(0);
+
+        var stdErr = FakeConsole.ReadErrorString();
         stdErr.Should().Contain("Failed to create an instance of type");
     }
-}
+}

CliFx.Tests/Utils/DynamicCommandBuilder.cs

@@ -11,14 +11,9 @@ using Microsoft.CodeAnalysis.Text;
 namespace CliFx.Tests.Utils;
 
 // This class uses Roslyn to compile commands dynamically.
-//
-// It allows us to collocate commands with tests more
-// easily, which helps a lot when reasoning about them.
-// Unfortunately, this comes at a cost of static typing,
-// but this is still a worthwhile trade off.
-//
-// Maybe one day C# will allow declaring classes inside
-// methods and doing this will no longer be necessary.
+// It allows us to collocate commands with tests more easily, which helps a lot when reasoning about them.
+// Unfortunately, this comes at a cost of static typing, but this is still a worthwhile trade off.
+// Maybe one day C# will allow declaring classes inside methods and doing this will no longer be necessary.
 // Language proposal: https://github.com/dotnet/csharplang/discussions/130
 internal static class DynamicCommandBuilder
 {
@@ -46,10 +41,10 @@ internal static class DynamicCommandBuilder
 
         // Append default imports to the source code
         var sourceCodeWithUsings =
-            string.Join(Environment.NewLine, defaultSystemNamespaces.Select(n => $"using {n};")) +
-            string.Join(Environment.NewLine, defaultCliFxNamespaces.Select(n => $"using {n};")) +
-            Environment.NewLine +
-            sourceCode;
+            string.Join(Environment.NewLine, defaultSystemNamespaces.Select(n => $"using {n};"))
+            + string.Join(Environment.NewLine, defaultCliFxNamespaces.Select(n => $"using {n};"))
+            + Environment.NewLine
+            + sourceCode;
 
         // Parse the source code
         var ast = SyntaxFactory.ParseSyntaxTree(
@@ -60,10 +55,16 @@ internal static class DynamicCommandBuilder
         // Compile the code to IL
         var compilation = CSharpCompilation.Create(
             "CliFxTests_DynamicAssembly_" + Guid.NewGuid(),
-            new[] {ast},
-            Net70.References.All
+            new[] { ast },
+            Net70
+                .References
+                .All
                 .Append(MetadataReference.CreateFromFile(typeof(ICommand).Assembly.Location))
-                .Append(MetadataReference.CreateFromFile(typeof(DynamicCommandBuilder).Assembly.Location)),
+                .Append(
+                    MetadataReference.CreateFromFile(
+                        typeof(DynamicCommandBuilder).Assembly.Location
+                    )
+                ),
             // DLL to avoid having to define the Main() method
             new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
         );
@@ -87,8 +88,7 @@ internal static class DynamicCommandBuilder
         using var buffer = new MemoryStream();
         var emit = compilation.Emit(buffer);
 
-        var emitErrors = emit
-            .Diagnostics
+        var emitErrors = emit.Diagnostics
             .Where(d => d.Severity >= DiagnosticSeverity.Error)
             .ToArray();
 
@@ -124,7 +124,6 @@ internal static class DynamicCommandBuilder
     public static Type Compile(string sourceCode)
     {
         var commandTypes = CompileMany(sourceCode);
-
         if (commandTypes.Count > 1)
         {
             throw new InvalidOperationException(
@@ -134,4 +133,4 @@ internal static class DynamicCommandBuilder
 
         return commandTypes.Single();
     }
-}
+}