Update version

Closes #132

.github/ISSUE_TEMPLATE/config.yml

@@ -1,5 +1,8 @@
 blank_issues_enabled: false
 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: 💬 Discord server
     url: https://discord.gg/2SUWKFnHSm
     about: Chat with the project community.

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -1,22 +0,0 @@
-name: ✨ Feature request
-description: Request a new feature.
-labels: [enhancement]
-
-body:
-- type: markdown
-  attributes:
-    value: |
-      🧐 **Guidelines:**
-
-      - Search through [existing issues](https://github.com/Tyrrrz/CliFx/issues?q=is%3Aissue) first to ensure that this feature has not been requested before.
-      - Write a descriptive title for your issue. Avoid generic or vague titles such as "Some suggestions" or "Ideas for improvement".
-      - Keep your issue focused on one single problem. If you have multiple feature requests, 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 requesting a feature, please use [discussions](https://github.com/Tyrrrz/CliFx/discussions/new) instead.
-
-- type: textarea
-  attributes:
-    label: Details
-    description: Clear and thorough explanation of the feature you have in mind.
-  validations:
-    required: true

.github/workflows/main.yml

@@ -6,7 +6,7 @@ jobs:
   main:
     uses: Tyrrrz/.github/.github/workflows/nuget.yml@master
     with:
-      dotnet-version: 6.0.x
+      dotnet-version: 7.0.x
     secrets:
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
       NUGET_TOKEN: ${{ secrets.NUGET_TOKEN }}

Changelog.md

@@ -1,10 +1,34 @@
-### v2.2.4 (22-Apr-2022)
+# Changelog
+
+## v2.3.2 (06-Apr-2023)
+
+- Added name-based ordering to subcommands when displayed in the help text. (Thanks [@CartBlanche](https://github.com/CartBlanche))
+
+## v2.3.1 (08-Dec-2022)
+
+- Added support for the `required` keyword introduced in C# 11. Command options bound to required properties are now marked as required by default (equivalent to setting `IsRequired = true` on the attribute). Also added analyzers that prevent marking an option or parameter non-required if it's bound to a required property.
+
+## v2.3 (12-Jul-2022)
+
+- Added console dimension properties `WindowWidth` and `WindowHeight` to `IConsole` interface and implementing classes.
+- Improved inline documentation for members of `IConsole` interface.
+
+## v2.2.6 (14-Jun-2022)
+
+- Added an overload of `CliApplicationBuilder.UseTypeActivator(...)` that accepts an instance of `IServiceProvider`. This slightly simplifies integration with many DI containers.
+- Fixed minor grammar mistakes in user-facing error messages.
+
+## v2.2.5 (10-May-2022)
+
+- Updated default value resolution for the application executable name. It will now resolve to `myapp.exe` instead of `dotnet myapp.dll` when the application is launched through the EXE apphost on Windows. On other platforms, or when running the application through the .NET CLI, the behavior will be the same as before.
+
+## v2.2.4 (22-Apr-2022)
 
 - Added more contextual information to analyzer diagnostics.
 - Fixed an issue where the analyzer incorrectly reported an error on converters that didn't directly match the target type but were compatible through known built-in conversions.
 - Fixed an issue where MSBuild produced a lot of analyzer-related warnings in certain circumstances.
 
-### v2.2.3 (17-Apr-2022)
+## v2.2.3 (17-Apr-2022)
 
 - Changed method signature of `IConsole.ReadKey()` to return `ConsoleKeyInfo` instead of `void`. The return type was originally defined as `void` by mistake. This change is source-backwards-compatible but may break on binary level if you were previously calling this method indirectly (i.e. through a library).
 - Added `FakeConsole.EnqueueKey(...)` to facilitate the testing of `IConsole.ReadKey()`. You can use this method to simulate key presses in your application.
@@ -12,57 +36,57 @@
 - Improved diagnostics produced by analyzers. Where relevant, highlighted code is now limited to the property or type identifier, instead of the whole property or type declaration. Also extended the diagnostic messages with additional information.
 - Fixed an issue where throwing an exception inside a constructor of a command type resulted in an unrelated error message about the absence of a parameterless constructor.
 
-### v2.2.2 (30-Jan-2022)
+## v2.2.2 (30-Jan-2022)
 
 - Fixed an issue where `ConsoleWriter` and `ConsoleReader` were not properly thread-safe.
 - Fixed an issue where the analyzer failed to load under certain circumstances when running inside Visual Studio.
 
-### v2.2.1 (16-Jan-2022)
+## v2.2.1 (16-Jan-2022)
 
 - Fixed an issue which caused help text to not show default values for optional parameters. (Thanks [@AliReZa Sabouri](https://github.com/alirezanet))
 
-### v2.2 (11-Jan-2022)
+## v2.2 (11-Jan-2022)
 
 - Added support for optional parameters. A parameter can be marked as optional by setting `IsRequired = false` on the attribute. Only one parameter is allowed to be optional and such parameter must be the last in order. (Thanks [@AliReZa Sabouri](https://github.com/alirezanet))
 - Fixed an issue where parameters and options bound to properties implemented as default interface members were not working correctly. (Thanks [@AliReZa Sabouri](https://github.com/alirezanet))
 
-### v2.1 (04-Jan-2022)
+## v2.1 (04-Jan-2022)
 
 - Added `IConsole.Clear()` with corresponding implementations in `SystemConsole`, `FakeConsole`, and `FakeInMemoryConsole`. (Thanks [@Alex Rosenfeld](https://github.com/alexrosenfeld10))
 - Added `IConsole.ReadKey()` with corresponding implementations in `SystemConsole`, `FakeConsole`, and `FakeInMemoryConsole`. (Thanks [@Alex Rosenfeld](https://github.com/alexrosenfeld10))
 - Fixed an issue that caused parameters to appear out of order in the usage format section of the help text. (Thanks [@David Fallah](https://github.com/TAGC))
 
-### v2.0.6 (17-Jul-2021)
+## v2.0.6 (17-Jul-2021)
 
 - Fixed an issue where an exception thrown via reflection during parameter or option binding resulted in `Exception has been thrown by the target of an invocation` error instead of a more useful message. Such exceptions will now be unwrapped to provide better user experience.
 
-### v2.0.5 (09-Jul-2021)
+## v2.0.5 (09-Jul-2021)
 
 - Fixed an issue where calling `IConsole.Output.Encoding.EncodingName` and some other members threw an exception.
 - Added readme file to the package.
 
-### v2.0.4 (24-Apr-2021)
+## v2.0.4 (24-Apr-2021)
 
 - Fixed an issue where output and error streams in `SystemConsole` defaulted to UTF8 encoding with BOM when the application was running with UTF8 codepage. `ConsoleWriter` will now discard preamble from the specified encoding. This fix brings the behavior of `SystemConsole` in line with .NET's own `System.Console` which also discards preamble for output and error streams.
 - Fixed an issue where help text tried to show default values for parameters and options whose type does not override `ToString()` method.
 - Fixed an issue where help text didn't show default values for parameters and options whose type is an enumerable of nullable enums. (Thanks [@Robert Dailey](https://github.com/rcdailey))
 - Fixed an issue where specific parts of the help text weren't legible in some terminals due to low color resolution. Removed the usage of `ConsoleColor.DarkGray` in help text.
 
-### v2.0.3 (09-Apr-2021)
+## v2.0.3 (09-Apr-2021)
 
 - Improved help text by showing valid values for non-scalar enum parameters and options. (Thanks [@Robert Dailey](https://github.com/rcdailey))
 
-### v2.0.2 (31-Mar-2021)
+## v2.0.2 (31-Mar-2021)
 
 - Fixed an issue where having a transitive reference to CliFx sometimes resulted in `SystemConsoleShouldBeAvoidedAnalyzer` throwing `NullReferenceException` during build.
 - Fixed some documentation typos and inconsistencies.
 
-### v2.0.1 (24-Mar-2021)
+## v2.0.1 (24-Mar-2021)
 
 - Fixed an issue where some exceptions with async stack traces generated on .NET 3.1 or earlier were not parsed and formatted correctly.
 - Fixed an issue where help text applied slightly incorrect formatting when displaying choices for enum-based parameters and properties.
 
-### v2.0 (21-Mar-2021)
+## v2.0 (21-Mar-2021)
 
 > Note: this major release includes many breaking changes.
 > Please refer to the readme to find updated instructions and usage examples.
@@ -82,7 +106,7 @@
   - Assigned separate colors to parameters and options to make them visually stand out
   - Usage section no longer lists usage formats of all descendant commands
   - Command section now also lists available subcommands for each of the current command's subcommands
-- Changed the behavior of `[preview]` directive. Running the application with this directive will now also print all resolved environment variables, in addition to parsed command line arguments.
+- Changed the behavior of `[preview]` directive. Running the application with this directive will now also print all resolved environment variables, in addition to parsed command-line arguments.
 - Reworked `IArgumentValueConverter`/`ArgumentValueConverter` into `BindingConverter`. Method `ConvertFrom(...)` has been renamed to `Convert(...)`.
 - Reworked `ArgumentValueValidator` into `BindingValidator`. This class exposes an abstract `Validate(...)` method that returns a nullable `BindingValidationError`. This class also provides utility methods `Ok()` and `Error(...)` to help create corresponding validation results.
 - Changed the type of `IConsole.Output` and `IConsole.Error` from `StreamWriter` to `ConsoleWriter`. This type derives from `StreamWriter` and additionally exposes a `Console` property that refers to the console instance that owns the stream. This change enables you to author extension methods scoped specifically to console output and error streams.
@@ -96,34 +120,34 @@
   - `ITypeActivator`/`DefaultTypeActivator`/`DelegateTypeActivator` moved from `CliFx` to `CliFx.Infrastructure`
   - `BindingValidator`/`BindingConverter` moved from `CliFx` to `CliFx.Extensibility`
 
-### v1.6 (06-Dec-2020)
+## v1.6 (06-Dec-2020)
 
 - Added support for custom value validators. You can now create a type that inherits from `CliFx.ArgumentValueValidator<T>` to implement reusable validation logic for command arguments. To use a validator, include it in the `Validators` property on the `CommandOption` or `CommandParameter` attribute. (Thanks [@Oleksandr Shustov](https://github.com/AlexandrShustov))
 - Added `CliFx.ArgumentValueConverter<T>` class that you can inherit from to implement custom value converters. `CliFx.IArgumentValueConverter` interface is still available, but it is recommended to inherit from the generic class instead, due to the type safety it provides. The interface may become internal or get removed in one of the future major versions.
 - Updated requirements for option names and short names: short names now must be letter characters (lowercase or uppercase), while names must now start with a letter character. This means option names can no longer start with a digit or a special character. This change makes it possible to pass negative number values without the need to quote them, i.e. `--my-number -5`.
 
-### v1.5 (23-Oct-2020)
+## v1.5 (23-Oct-2020)
 
 - Added pretty-printing for unhandled exceptions thrown from within the application. This makes the errors easier to parse visually and should help in troubleshooting. This change does not affect `CommandException`, as it already has special treatment. (Thanks [@Mårten Åsberg](https://github.com/89netraM))
 - Added support for custom value converters. You can now create a type that implements `CliFx.IArgumentValueConverter` and specify it as a converter for your parameters or options via the `Converter` named property. This should enable conversion between raw argument values and custom types which are not string-initializable. (Thanks [@Oleksandr Shustov](https://github.com/AlexandrShustov))
 - Improved help text so that it also shows minimal usage examples for child and descendant commands, besides the actual command it was requested on. This should improve user experience for applications with many nested commands. (Thanks [@Nikiforov Alexey](https://github.com/NikiforovAll))
 
-### v1.4 (20-Aug-2020)
+## v1.4 (20-Aug-2020)
 
 - Added `VirtualConsole.CreateBuffered()` method to simplify test setup when using in-memory backing stores for output and error streams. Please refer to the readme for updated recommendations on how to test applications built with CliFx.
 - Added generic `CliApplicationBuilder.AddCommand<TCommand>()`. This overload simplifies adding commands one-by-one as it also checks that the type implements `ICommand`.
 
-### v1.3.2 (31-Jul-2020)
+## v1.3.2 (31-Jul-2020)
 
 - Fixed an issue where a command was incorrectly allowed to execute when the user did not specify any value for a non-scalar parameter. Since they are always required, a parameter needs to be bound to at least one value. (Thanks [@Daniel Hix](https://github.com/ADustyOldMuffin))
 - Fixed an issue where `CliApplication.RunAsync(...)` threw `ArgumentException` if there were two environment variables, whose names differed only in case. Environment variable names are now treated case-sensitively. (Thanks [@Ron Myers](https://github.com/ron-myers))
 
-### v1.3.1 (19-Jul-2020)
+## v1.3.1 (19-Jul-2020)
 
 - Running the application with the debug directive (`myapp [debug]`) will now also try to launch a debugger instance. In most cases it will save time as you won't need to attach the debugger manually. (Thanks [@Volodymyr Shkolka](https://github.com/BlackGad))
 - Fixed an issue where unhandled generic exceptions (i.e. not `CommandException`) sometimes caused the application to incorrectly return successful exit code due to an overflow issue on Unix systems. Starting from this version, all unhandled generic exceptions will produce `1` as the exit code when thrown. Instances of `CommandException` can still be configured to return any specified exit code, but it's recommended to constrain the values between `1` and `255` to avoid overflow issues. (Thanks [@Ihor Nechyporuk](https://github.com/inech))
 
-### v1.3 (23-May-2020)
+## v1.3 (23-May-2020)
 
 - Changed analyzers to report errors instead of warnings. If you find that some analyzer works incorrectly, please report it on GitHub. You can also configure inspection severity overrides in your project if you need to.
 - Improved help text by showing default values for non-required options. This only works on types that have a custom override for `ToString()` method. Additionally, if the type implements `IFormattable`, the overload with a format provider will be used instead. (Thanks [@Domn Werner](https://github.com/domn1995))
@@ -131,7 +155,7 @@
 - Fixed an issue where it was possible to define a command with an option that has the same name or short name as built-in help or version options. Previously it would lead to the user-defined option being ignored in favor of the built-in option. Now this will throw an exception instead.
 - Changed the underlying representation of `StreamReader`/`StreamWriter` objects used in `SystemConsole` and `VirtualConsole` to be thread-safe.
 
-### v1.2 (11-May-2020)
+## v1.2 (11-May-2020)
 
 - Added built-in Roslyn analyzers that help catch incorrect usage of the library. Currently, all analyzers report issues as warnings so as to not prevent the project from building. In the future that may change.
 - Added an optional parameter to `new CommandException(...)` called `showHelp` which can be used to instruct CliFx to show help for the current command after printing the error. (Thanks [@Domn Werner](https://github.com/domn1995))
@@ -142,7 +166,7 @@
 - Improved exception messages.
 - Improved exceptions related to user input by also showing help text after the error message. (Thanks [@Domn Werner](https://github.com/domn1995))
 
-### v1.1 (16-Mar-2020)
+## v1.1 (16-Mar-2020)
 
 - Changed `IConsole` interface (and as a result, `SystemConsole` and `VirtualConsole`) to support writing binary data. Instead of `TextReader`/`TextWriter` instances, the streams are now exposed as `StreamReader`/`StreamWriter` which provide the `BaseStream` property that allows raw access. Existing usages inside commands should remain the same because `StreamReader`/`StreamWriter` are compatible with their base classes `TextReader`/`TextWriter`, but if you were using `VirtualConsole` in tests, you may have to update it to the new API. Refer to the readme for more info.
 - Changed argument binding behavior so that an error is produced if the user provides an argument that doesn't match with any parameter or option. This is done in order to improve user experience, as otherwise the user may make a typo without knowing that their input wasn't taken into account.

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

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
@@ -9,14 +9,14 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Basic.Reference.Assemblies" Version="1.2.4" />
-    <PackageReference Include="GitHubActionsTestLogger" Version="1.4.1" PrivateAssets="all" />
-    <PackageReference Include="FluentAssertions" Version="6.6.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.1.0" />
-    <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" PrivateAssets="all" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" PrivateAssets="all" />
+    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.1" />
+    <PackageReference Include="GitHubActionsTestLogger" Version="2.0.1" PrivateAssets="all" />
+    <PackageReference Include="FluentAssertions" Version="6.10.0" />
+    <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" />
   </ItemGroup>
 
   <ItemGroup>

CliFx.Analyzers.Tests/CommandMustBeAnnotatedAnalyzerSpecs.cs

@@ -13,11 +13,13 @@ public class CommandMustBeAnnotatedAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -28,12 +30,14 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public abstract class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -44,11 +48,13 @@ public abstract class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public abstract class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -59,11 +65,13 @@ public abstract class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class Foo
             {
                 public int Bar { get; set; } = 5;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/CommandMustImplementInterfaceAnalyzerSpecs.cs

@@ -13,12 +13,14 @@ public class CommandMustImplementInterfaceAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -29,12 +31,14 @@ public class MyCommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -45,11 +49,13 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class Foo
             {
                 public int Bar { get; set; } = 5;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustBeInsideCommandAnalyzerSpecs.cs

@@ -13,12 +13,14 @@ public class OptionMustBeInsideCommandAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyClass
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -29,15 +31,17 @@ public class MyClass
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -48,12 +52,14 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public abstract class MyCommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -64,14 +70,16 @@ public abstract class MyCommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs.cs

@@ -0,0 +1,114 @@
+using CliFx.Analyzers.Tests.Utils;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Xunit;
+
+namespace CliFx.Analyzers.Tests;
+
+public class OptionMustBeRequiredIfPropertyRequiredAnalyzerSpecs
+{
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandOption('f', IsRequired = false)]
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().ProduceDiagnostics(code);
+    }
+
+    [Fact]
+    public void Analyzer_does_not_report_an_error_if_a_required_option_is_bound_to_a_required_property()
+    {
+        // Arrange
+        // language=cs
+        const string code =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandOption('f', IsRequired = true)]
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandOption('f', IsRequired = false)]
+                public string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandOption('f', IsRequired = true)]
+                public string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_an_option()
+    {
+        // Arrange
+        // language=cs
+        const string code =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+}

CliFx.Analyzers.Tests/OptionMustHaveNameOrShortNameAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class OptionMustHaveNameOrShortNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -21,7 +22,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -32,15 +34,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -51,7 +55,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -59,7 +64,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -70,14 +76,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveUniqueNameAnalyzerSpecs.cs

@@ -13,18 +13,20 @@ public class OptionMustHaveUniqueNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,18 +37,20 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
-    [CommandOption(""bar"")]
+                [CommandOption("bar")]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,7 +61,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -65,7 +70,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -76,14 +82,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveUniqueShortNameAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class OptionMustHaveUniqueShortNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -24,7 +25,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,7 +37,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -46,7 +49,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,7 +61,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -68,7 +73,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -79,15 +85,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -98,14 +106,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveValidConverterAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class OptionMustHaveValidConverterAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter
             {
                 public string Convert(string rawValue) => rawValue;
@@ -22,11 +23,12 @@ public class MyConverter
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -37,7 +39,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<int>
             {
                 public override int Convert(string rawValue) => 42;
@@ -46,11 +49,12 @@ public class MyConverter : BindingConverter<int>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -61,7 +65,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<string>
             {
                 public override string Convert(string rawValue) => rawValue;
@@ -70,11 +75,12 @@ public class MyConverter : BindingConverter<string>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -85,7 +91,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<int>
             {
                 public override int Convert(string rawValue) => 42;
@@ -94,11 +101,12 @@ public class MyConverter : BindingConverter<int>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public int? Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -109,7 +117,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<string>
             {
                 public override string Convert(string rawValue) => rawValue;
@@ -118,11 +127,12 @@ public class MyConverter : BindingConverter<string>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public IReadOnlyList<string> Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -133,15 +143,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -152,14 +164,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveValidNameAnalyzerSpecs.cs

@@ -13,15 +13,17 @@ public class OptionMustHaveValidNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""f"")]
+                [CommandOption("f")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -32,15 +34,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""1foo"")]
+                [CommandOption("1foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -51,15 +55,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -70,7 +76,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -78,7 +85,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -89,14 +97,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveValidShortNameAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class OptionMustHaveValidShortNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -21,7 +22,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -32,7 +34,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -40,7 +43,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -51,15 +55,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -70,14 +76,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/OptionMustHaveValidValidatorsAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class OptionMustHaveValidValidatorsAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator
             {
                 public void Validate(string value) {}
@@ -22,11 +23,12 @@ public class MyValidator
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Validators = new[] {typeof(MyValidator)})]
+                [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -37,7 +39,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator : BindingValidator<int>
             {
                 public override BindingValidationError Validate(int value) => Ok();
@@ -46,11 +49,12 @@ public class MyValidator : BindingValidator<int>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Validators = new[] {typeof(MyValidator)})]
+                [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -61,7 +65,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator : BindingValidator<string>
             {
                 public override BindingValidationError Validate(string value) => Ok();
@@ -70,11 +75,12 @@ public class MyValidator : BindingValidator<string>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Validators = new[] {typeof(MyValidator)})]
+                [CommandOption("foo", Validators = new[] {typeof(MyValidator)})]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -85,15 +91,17 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -104,14 +112,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustBeInsideCommandAnalyzerSpecs.cs

@@ -13,12 +13,14 @@ public class ParameterMustBeInsideCommandAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyClass
             {
                 [CommandParameter(0)]
                 public string Foo { get; set; }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -29,7 +31,8 @@ public class MyClass
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -37,7 +40,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -48,12 +52,14 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public abstract class MyCommand
             {
                 [CommandParameter(0)]
                 public string Foo { get; set; }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -64,14 +70,16 @@ public abstract class MyCommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustBeLastIfNonRequiredAnalyzerSpecs.cs

@@ -13,18 +13,20 @@ public class ParameterMustBeLastIfNonRequiredAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandParameter(0, Name = ""foo"", IsRequired = false)]
+                [CommandParameter(0, IsRequired = false)]
                 public string Foo { get; set; }
             
-    [CommandParameter(1, Name = ""bar"")]
+                [CommandParameter(1)]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,18 +37,20 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandParameter(0, Name = ""foo"")]
+                [CommandParameter(0)]
                 public string Foo { get; set; }
             
-    [CommandParameter(1, Name = ""bar"", IsRequired = false)]
+                [CommandParameter(1, IsRequired = false)]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,18 +61,20 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandParameter(0, Name = ""foo"")]
+                [CommandParameter(0)]
                 public string Foo { get; set; }
             
-    [CommandParameter(1, Name = ""bar"", IsRequired = true)]
+                [CommandParameter(1, IsRequired = true)]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -79,14 +85,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustBeLastIfNonScalarAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustBeLastIfNonScalarAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -24,7 +25,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,7 +37,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -46,7 +49,8 @@ public class MyCommand : ICommand
                 public string[] Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,7 +61,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -68,7 +73,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -79,14 +85,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs.cs

@@ -0,0 +1,114 @@
+using CliFx.Analyzers.Tests.Utils;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Xunit;
+
+namespace CliFx.Analyzers.Tests;
+
+public class ParameterMustBeRequiredIfPropertyRequiredAnalyzerSpecs
+{
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandParameter(0, IsRequired = false)]
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().ProduceDiagnostics(code);
+    }
+
+    [Fact]
+    public void Analyzer_does_not_report_an_error_if_a_required_parameter_is_bound_to_a_required_property()
+    {
+        // Arrange
+        // language=cs
+        const string code =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandParameter(0, IsRequired = true)]
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandParameter(0, IsRequired = false)]
+                public string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    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 =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                [CommandParameter(0, IsRequired = true)]
+                public string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+
+    [Fact]
+    public void Analyzer_does_not_report_an_error_on_a_property_that_is_not_a_parameter()
+    {
+        // Arrange
+        // language=cs
+        const string code =
+            """
+            [Command]
+            public class MyCommand : ICommand
+            {
+                public required string Foo { get; set; }
+
+                public ValueTask ExecuteAsync(IConsole console) => default;
+            }
+            """;
+
+        // Act & assert
+        Analyzer.Should().NotProduceDiagnostics(code);
+    }
+}

CliFx.Analyzers.Tests/ParameterMustBeSingleIfNonRequiredAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustBeSingleIfNonRequiredAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -24,7 +25,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,7 +37,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -46,7 +49,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,7 +61,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -68,7 +73,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -79,14 +85,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustBeSingleIfNonScalarAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustBeSingleIfNonScalarAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -24,7 +25,8 @@ public class MyCommand : ICommand
                 public string[] Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,7 +37,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -46,7 +49,8 @@ public class MyCommand : ICommand
                 public string[] Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,7 +61,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -68,7 +73,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -79,14 +85,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustHaveUniqueNameAnalyzerSpecs.cs

@@ -13,18 +13,20 @@ public class ParameterMustHaveUniqueNameAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandParameter(0, Name = ""foo"")]
+                [CommandParameter(0, Name = "foo")]
                 public string Foo { get; set; }
             
-    [CommandParameter(1, Name = ""foo"")]
+                [CommandParameter(1, Name = "foo")]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,18 +37,20 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandParameter(0, Name = ""foo"")]
+                [CommandParameter(0, Name = "foo")]
                 public string Foo { get; set; }
             
-    [CommandParameter(1, Name = ""bar"")]
+                [CommandParameter(1, Name = "bar")]
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,14 +61,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustHaveUniqueOrderAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustHaveUniqueOrderAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -24,7 +25,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -35,7 +37,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -46,7 +49,8 @@ public class MyCommand : ICommand
                 public string Bar { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -57,14 +61,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustHaveValidConverterAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustHaveValidConverterAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter
             {
                 public string Convert(string rawValue) => rawValue;
@@ -26,7 +27,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -37,7 +39,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<int>
             {
                 public override int Convert(string rawValue) => 42;
@@ -50,7 +53,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
 
         // Act & assert
@@ -62,7 +66,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<string>
             {
                 public override string Convert(string rawValue) => rawValue;
@@ -75,7 +80,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -86,7 +92,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<int>
             {
                 public override int Convert(string rawValue) => 42;
@@ -95,11 +102,12 @@ public class MyConverter : BindingConverter<int>
             [Command]
             public class MyCommand : ICommand
             {
-    [CommandOption(""foo"", Converter = typeof(MyConverter))]
+                [CommandOption("foo", Converter = typeof(MyConverter))]
                 public int? Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -110,7 +118,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyConverter : BindingConverter<string>
             {
                 public override string Convert(string rawValue) => rawValue;
@@ -123,7 +132,8 @@ public class MyCommand : ICommand
                 public IReadOnlyList<string> Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -134,7 +144,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -142,7 +153,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -153,14 +165,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/ParameterMustHaveValidValidatorsAnalyzerSpecs.cs

@@ -13,7 +13,8 @@ public class ParameterMustHaveValidValidatorsAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator
             {
                 public void Validate(string value) {}
@@ -26,7 +27,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -37,7 +39,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator : BindingValidator<int>
             {
                 public override BindingValidationError Validate(int value) => Ok();
@@ -50,7 +53,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -61,7 +65,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             public class MyValidator : BindingValidator<string>
             {
                 public override BindingValidationError Validate(string value) => Ok();
@@ -74,7 +79,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -85,7 +91,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -93,7 +100,8 @@ public class MyCommand : ICommand
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -104,14 +112,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public string Foo { get; set; }
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/SystemConsoleShouldBeAvoidedAnalyzerSpecs.cs

@@ -13,16 +13,18 @@ public class SystemConsoleShouldBeAvoidedAnalyzerSpecs
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        Console.WriteLine(""Hello world"");
+                    Console.WriteLine("Hello world");
                     return default;
                 }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -33,7 +35,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -42,7 +45,9 @@ public class MyCommand : ICommand
                     Console.ForegroundColor = ConsoleColor.Black;
                     return default;
                 }
-}";
+            }
+            """;
+
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
     }
@@ -52,16 +57,18 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        Console.Error.WriteLine(""Hello world"");
+                    Console.Error.WriteLine("Hello world");
                     return default;
                 }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().ProduceDiagnostics(code);
@@ -72,16 +79,18 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Hello world"");
+                    console.Output.WriteLine("Hello world");
                     return default;
                 }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -92,14 +101,16 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
-    public void SomeOtherMethod() => Console.WriteLine(""Test"");
+                public void SomeOtherMethod() => Console.WriteLine("Test");
             
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);
@@ -110,7 +121,8 @@ public class MyCommand : ICommand
     {
         // Arrange
         // language=cs
-        const string code = @"
+        const string code =
+            """
             [Command]
             public class MyCommand : ICommand
             {
@@ -118,7 +130,8 @@ public class MyCommand : ICommand
                 {
                     return default;
                 }
-}";
+            }
+            """;
 
         // Act & assert
         Analyzer.Should().NotProduceDiagnostics(code);

CliFx.Analyzers.Tests/Utils/AnalyzerAssertions.cs

@@ -58,7 +58,7 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
         var compilation = CSharpCompilation.Create(
             "CliFxTests_DynamicAssembly_" + Guid.NewGuid(),
             new[] { ast },
-            ReferenceAssemblies.Net50
+            Net70.References.All
                 .Append(MetadataReference.CreateFromFile(typeof(ICommand).Assembly.Location)),
             // DLL to avoid having to define the Main() method
             new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
@@ -72,9 +72,10 @@ internal class AnalyzerAssertions : ReferenceTypeAssertions<DiagnosticAnalyzer,
         if (compilationErrors.Any())
         {
             throw new InvalidOperationException(
-                "Failed to compile code." +
-                Environment.NewLine +
-                string.Join(Environment.NewLine, compilationErrors.Select(e => e.ToString()))
+                $"""
+                Failed to compile code.
+                {string.Join(Environment.NewLine, compilationErrors.Select(e => e.ToString()))}
+                """
             );
         }
 

CliFx.Analyzers/CliFx.Analyzers.csproj

@@ -3,14 +3,23 @@
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
     <CopyLocalLockFileAssemblies>true</CopyLocalLockFileAssemblies>
-    <Nullable>annotations</Nullable>
+    <GenerateDependencyFile>true</GenerateDependencyFile>
+    <EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
     <NoWarn>$(NoWarn);RS1025;RS1026</NoWarn>
   </PropertyGroup>
 
+  <PropertyGroup>
+    <!--
+      Because this project only has a single target framework, the condition in
+      Directory.Build.props does not appear to work. This is a workaround for that.
+    -->
+    <Nullable>annotations</Nullable>
+  </PropertyGroup>
+
   <ItemGroup>
-    <!-- Keep this dependency as low as possible since we can't bundle it -->
-    <!-- https://github.com/Tyrrrz/CliFx/issues/127 -->
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="3.8.0" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.Analyzers" Version="3.3.4" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.5.0" PrivateAssets="all" />
+    <PackageReference Include="PolyShim" Version="1.1.0" PrivateAssets="all" />
   </ItemGroup>
 
 </Project>

CliFx.Analyzers/ObjectModel/CommandOptionSymbol.cs

@@ -13,6 +13,8 @@ internal partial class CommandOptionSymbol : ICommandMemberSymbol
 
     public char? ShortName { get; }
 
+    public bool? IsRequired { get; }
+
     public ITypeSymbol? ConverterType { get; }
 
     public IReadOnlyList<ITypeSymbol> ValidatorTypes { get; }
@@ -21,12 +23,14 @@ internal partial class CommandOptionSymbol : ICommandMemberSymbol
         IPropertySymbol property,
         string? name,
         char? shortName,
+        bool? isRequired,
         ITypeSymbol? converterType,
         IReadOnlyList<ITypeSymbol> validatorTypes)
     {
         Property = property;
         Name = name;
         ShortName = shortName;
+        IsRequired = isRequired;
         ConverterType = converterType;
         ValidatorTypes = validatorTypes;
     }
@@ -56,6 +60,12 @@ internal partial class CommandOptionSymbol
             .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 converter = attribute
             .NamedArguments
             .Where(a => a.Key == "Converter")
@@ -71,7 +81,7 @@ internal partial class CommandOptionSymbol
             .Cast<ITypeSymbol>()
             .ToArray();
 
-        return new CommandOptionSymbol(property, name, shortName, converter, validators);
+        return new CommandOptionSymbol(property, name, shortName, isRequired, converter, validators);
     }
 
     public static bool IsOptionProperty(IPropertySymbol property) =>

CliFx.Analyzers/OptionMustBeRequiredIfPropertyRequiredAnalyzer.cs

@@ -0,0 +1,49 @@
+using CliFx.Analyzers.ObjectModel;
+using CliFx.Analyzers.Utils.Extensions;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace CliFx.Analyzers;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+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.")
+    {
+    }
+
+    private void Analyze(
+        SyntaxNodeAnalysisContext context,
+        PropertyDeclarationSyntax propertyDeclaration,
+        IPropertySymbol property)
+    {
+        if (property.ContainingType is null)
+            return;
+
+        if (!property.IsRequired)
+            return;
+
+        var option = CommandOptionSymbol.TryResolve(property);
+        if (option is null)
+            return;
+
+        if (option.IsRequired != false)
+            return;
+
+        context.ReportDiagnostic(
+            CreateDiagnostic(
+                propertyDeclaration.Identifier.GetLocation()
+            )
+        );
+    }
+
+    public override void Initialize(AnalysisContext context)
+    {
+        base.Initialize(context);
+        context.HandlePropertyDeclaration(Analyze);
+    }
+}

CliFx.Analyzers/ParameterMustBeRequiredIfPropertyRequiredAnalyzer.cs

@@ -0,0 +1,49 @@
+using CliFx.Analyzers.ObjectModel;
+using CliFx.Analyzers.Utils.Extensions;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace CliFx.Analyzers;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+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.")
+    {
+    }
+
+    private void Analyze(
+        SyntaxNodeAnalysisContext context,
+        PropertyDeclarationSyntax propertyDeclaration,
+        IPropertySymbol property)
+    {
+        if (property.ContainingType is null)
+            return;
+
+        if (!property.IsRequired)
+            return;
+
+        var parameter = CommandParameterSymbol.TryResolve(property);
+        if (parameter is null)
+            return;
+
+        if (parameter.IsRequired != false)
+            return;
+
+        context.ReportDiagnostic(
+            CreateDiagnostic(
+                propertyDeclaration.Identifier.GetLocation()
+            )
+        );
+    }
+
+    public override void Initialize(AnalysisContext context)
+    {
+        base.Initialize(context);
+        context.HandlePropertyDeclaration(Analyze);
+    }
+}

CliFx.Analyzers/Utils/Extensions/StringExtensions.cs

@@ -10,7 +10,7 @@ internal static class StringExtensions
         StringComparison comparison = StringComparison.Ordinal)
     {
         while (str.EndsWith(sub, comparison))
-            str = str.Substring(0, str.Length - sub.Length);
+            str = str[..^sub.Length];
 
         return str;
     }

CliFx.Benchmarks/CliFx.Benchmarks.csproj

@@ -2,16 +2,16 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.13.1" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.13.5" />
     <PackageReference Include="clipr" Version="1.6.1" />
-    <PackageReference Include="Cocona" Version="2.0.3" />
-    <PackageReference Include="CommandLineParser" Version="2.8.0" />
-    <PackageReference Include="McMaster.Extensions.CommandLineUtils" Version="4.0.1" />
-    <PackageReference Include="PowerArgs" Version="3.6.0" />
+    <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="System.CommandLine" Version="2.0.0-beta1.20574.7" />
   </ItemGroup>
 

CliFx.Demo/CliFx.Demo.csproj

@@ -2,12 +2,11 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="6.0.0" />
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.1" />
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="7.0.0" />
   </ItemGroup>
 
   <ItemGroup>

CliFx.Demo/Commands/BookAddCommand.cs

@@ -14,10 +14,10 @@ public partial class BookAddCommand : ICommand
     private readonly LibraryProvider _libraryProvider;
 
     [CommandParameter(0, Name = "title", Description = "Book title.")]
-    public string Title { get; init; } = "";
+    public required string Title { get; init; }
 
     [CommandOption("author", 'a', IsRequired = true, Description = "Book author.")]
-    public string Author { get; init; } = "";
+    public required string Author { get; init; }
 
     [CommandOption("published", 'p', Description = "Book publish date.")]
     public DateTimeOffset Published { get; init; } = CreateRandomDate();

CliFx.Demo/Commands/BookCommand.cs

@@ -13,7 +13,7 @@ public class BookCommand : ICommand
     private readonly LibraryProvider _libraryProvider;
 
     [CommandParameter(0, Name = "title", Description = "Title of the book to retrieve.")]
-    public string Title { get; init; } = "";
+    public required string Title { get; init; }
 
     public BookCommand(LibraryProvider libraryProvider)
     {

CliFx.Demo/Commands/BookRemoveCommand.cs

@@ -12,7 +12,7 @@ public class BookRemoveCommand : ICommand
     private readonly LibraryProvider _libraryProvider;
 
     [CommandParameter(0, Name = "title", Description = "Title of the book to remove.")]
-    public string Title { get; init; } = "";
+    public required string Title { get; init; }
 
     public BookRemoveCommand(LibraryProvider libraryProvider)
     {

CliFx.Demo/Domain/Book.cs

@@ -2,21 +2,4 @@
 
 namespace CliFx.Demo.Domain;
 
-public class Book
-{
-    public string Title { get; }
-
-    public string Author { get; }
-
-    public DateTimeOffset Published { get; }
-
-    public Isbn Isbn { get; }
-
-    public Book(string title, string author, DateTimeOffset published, Isbn isbn)
-    {
-        Title = title;
-        Author = author;
-        Published = published;
-        Isbn = isbn;
-    }
-}
+public record Book(string Title, string Author, DateTimeOffset Published, Isbn Isbn);

CliFx.Demo/Domain/Isbn.cs

@@ -2,32 +2,13 @@
 
 namespace CliFx.Demo.Domain;
 
-public partial class Isbn
+public partial record Isbn(int EanPrefix, int RegistrationGroup, int Registrant, int Publication, int CheckDigit)
 {
-    public int EanPrefix { get; }
-
-    public int RegistrationGroup { get; }
-
-    public int Registrant { get; }
-
-    public int Publication { get; }
-
-    public int CheckDigit { get; }
-
-    public Isbn(int eanPrefix, int registrationGroup, int registrant, int publication, int checkDigit)
-    {
-        EanPrefix = eanPrefix;
-        RegistrationGroup = registrationGroup;
-        Registrant = registrant;
-        Publication = publication;
-        CheckDigit = checkDigit;
-    }
-
     public override string ToString() =>
         $"{EanPrefix:000}-{RegistrationGroup:00}-{Registrant:00000}-{Publication:00}-{CheckDigit:0}";
 }
 
-public partial class Isbn
+public partial record Isbn
 {
     public static Isbn Parse(string value, IFormatProvider formatProvider)
     {

CliFx.Demo/Domain/Library.cs

@@ -4,15 +4,8 @@ using System.Linq;
 
 namespace CliFx.Demo.Domain;
 
-public partial class Library
+public partial record Library(IReadOnlyList<Book> Books)
 {
-    public IReadOnlyList<Book> Books { get; }
-
-    public Library(IReadOnlyList<Book> books)
-    {
-        Books = books;
-    }
-
     public Library WithBook(Book book)
     {
         var books = Books.ToList();
@@ -29,7 +22,7 @@ public partial class Library
     }
 }
 
-public partial class Library
+public partial record Library
 {
     public static Library Empty { get; } = new(Array.Empty<Book>());
 }

CliFx.Demo/Domain/LibraryProvider.cs

@@ -1,6 +1,6 @@
 using System.IO;
 using System.Linq;
-using Newtonsoft.Json;
+using System.Text.Json;
 
 namespace CliFx.Demo.Domain;
 
@@ -10,7 +10,7 @@ public class LibraryProvider
 
     private void StoreLibrary(Library library)
     {
-        var data = JsonConvert.SerializeObject(library);
+        var data = JsonSerializer.Serialize(library);
         File.WriteAllText(StorageFilePath, data);
     }
 
@@ -21,7 +21,7 @@ public class LibraryProvider
 
         var data = File.ReadAllText(StorageFilePath);
 
-        return JsonConvert.DeserializeObject<Library>(data) ?? Library.Empty;
+        return JsonSerializer.Deserialize<Library>(data) ?? Library.Empty;
     }
 
     public Book? TryGetBook(string title) => GetLibrary().Books.FirstOrDefault(b => b.Title == title);

CliFx.Demo/Readme.md

@@ -1,5 +1,5 @@
 # CliFx Demo Project
 
-Sample command line interface for managing a library of books.
+Sample command-line interface for managing a library of books.
 
-This demo project showcases basic CliFx functionality such as command routing, argument parsing, autogenerated help text.
+This demo project showcases basic CliFx functionality such as command routing, argument parsing, and autogenerated help text.

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

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

CliFx.Tests.Dummy/Program.cs

@@ -3,12 +3,13 @@ using System.Reflection;
 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
 {
-    public static Assembly Assembly { get; } = typeof(Program).Assembly;
+    public static Assembly Assembly { get; } = Assembly.GetExecutingAssembly();
 
     public static string Location { get; } = Assembly.Location;
 }

CliFx.Tests/CancellationSpecs.cs

@@ -16,12 +16,12 @@ public class CancellationSpecs : SpecsBase
     }
 
     [Fact]
-    public async Task Command_can_register_to_receive_a_cancellation_signal_from_the_console()
+    public async Task Command_can_receive_a_cancellation_signal_from_the_console()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -34,15 +34,17 @@ public class Command : ICommand
                             console.RegisterCancellationHandler()
                         );
 
-            console.Output.WriteLine(""Completed successfully"");
+                        console.Output.WriteLine("Completed successfully");
                     }
                     catch (OperationCanceledException)
                     {
-            console.Output.WriteLine(""Cancelled"");
+                        console.Output.WriteLine("Cancelled");
                         throw;
                     }
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/CliFx.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net7.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>
@@ -9,15 +9,16 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Basic.Reference.Assemblies" Version="1.2.4" />
-    <PackageReference Include="CliWrap" Version="3.4.3" />
-    <PackageReference Include="FluentAssertions" Version="6.6.0" />
-    <PackageReference Include="GitHubActionsTestLogger" Version="1.4.1" PrivateAssets="all" />
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.1.0" />
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
-    <PackageReference Include="xunit" Version="2.4.1" />
-    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3" PrivateAssets="all" />
-    <PackageReference Include="coverlet.collector" Version="3.1.2" PrivateAssets="all" />
+    <PackageReference Include="Basic.Reference.Assemblies.Net70" Version="1.4.1" />
+    <PackageReference Include="CliWrap" Version="3.6.0" />
+    <PackageReference Include="FluentAssertions" Version="6.10.0" />
+    <PackageReference Include="GitHubActionsTestLogger" Version="2.0.1" 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" />
   </ItemGroup>
 
   <ItemGroup>
@@ -25,12 +26,4 @@
     <ProjectReference Include="..\CliFx\CliFx.csproj" />
   </ItemGroup>
 
-  <ItemGroup>
-    <None Include="../CliFx.Tests.Dummy/bin/$(Configuration)/$(TargetFramework)/CliFx.Tests.Dummy.runtimeconfig.json">
-      <Link>CliFx.Tests.Dummy.runtimeconfig.json</Link>
-      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
-      <Visible>false</Visible>
-    </None>
-  </ItemGroup>
-
 </Project>

CliFx.Tests/ConsoleSpecs.cs

@@ -21,7 +21,7 @@ public class ConsoleSpecs : SpecsBase
     {
     }
 
-    [Fact]
+    [Fact(Timeout = 15000)]
     public async Task Real_console_maps_directly_to_system_console()
     {
         // Can't verify our own console output, so using an
@@ -31,7 +31,8 @@ public class ConsoleSpecs : SpecsBase
         var command = "Hello world" | Cli.Wrap("dotnet")
             .WithArguments(a => a
                 .Add(Dummy.Program.Location)
-                .Add("console-test"));
+                .Add("console-test")
+            );
 
         // Act
         var result = await command.ExecuteBufferedAsync();
@@ -47,7 +48,7 @@ public class ConsoleSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -56,16 +57,19 @@ public class Command : ICommand
                     console.ResetColor();
                     console.ForegroundColor = ConsoleColor.DarkMagenta;
                     console.BackgroundColor = ConsoleColor.DarkMagenta;
+                    console.WindowWidth = 100;
+                    console.WindowHeight = 25;
                     console.CursorLeft = 42;
                     console.CursorTop = 24;
 
-        console.Output.WriteLine(""Hello "");
-        console.Error.WriteLine(""world!"");
+                    console.Output.WriteLine("Hello ");
+                    console.Error.WriteLine("world!");
 
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -89,6 +93,8 @@ public class Command : ICommand
         Console.BackgroundColor.Should().NotBe(ConsoleColor.DarkMagenta);
 
         // This fails because tests don't spawn a console window
+        //Console.WindowWidth.Should().Be(100);
+        //Console.WindowHeight.Should().Be(25);
         //Console.CursorLeft.Should().NotBe(42);
         //Console.CursorTop.Should().NotBe(24);
 
@@ -103,7 +109,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -116,7 +122,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -146,7 +153,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -159,7 +166,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/ConversionSpecs.cs

@@ -21,7 +21,7 @@ public class ConversionSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -34,7 +34,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -59,7 +61,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -72,7 +74,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -97,7 +101,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -109,13 +113,15 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -143,7 +149,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -156,7 +162,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -181,7 +189,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -194,7 +202,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -219,7 +229,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -232,7 +242,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -257,7 +269,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -266,11 +278,13 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(Foo.ToString(""u"", CultureInfo.InvariantCulture));
+                    console.Output.WriteLine(Foo.ToString("u", CultureInfo.InvariantCulture));
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -295,7 +309,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -308,7 +322,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -333,7 +349,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public enum CustomEnum { One = 1, Two = 2, Three = 3 }
 
             [Command]
@@ -348,7 +364,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -373,7 +391,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -385,13 +403,15 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -419,7 +439,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public enum CustomEnum { One = 1, Two = 2, Three = 3 }
 
             [Command]
@@ -433,13 +453,15 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + (int?) Foo);
-        console.Output.WriteLine(""Bar = "" + (int?) Bar);
+                    console.Output.WriteLine("Foo = " + (int?) Foo);
+                    console.Output.WriteLine("Bar = " + (int?) Bar);
 
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -467,7 +489,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomType
             {
                 public string Value { get; }
@@ -487,7 +509,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -512,7 +536,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomTypeA
             {
                 public string Value { get; }
@@ -544,13 +568,15 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo.Value);
-        console.Output.WriteLine(""Bar = "" + Bar.Value);
+                    console.Output.WriteLine("Foo = " + Foo.Value);
+                    console.Output.WriteLine("Bar = " + Bar.Value);
 
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -578,7 +604,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomConverter : BindingConverter<int>
             {
                 public override int Convert(string rawValue) =>
@@ -597,7 +623,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -622,7 +650,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -637,7 +665,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -666,7 +696,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -681,7 +711,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -710,7 +742,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -725,7 +757,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -754,7 +788,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -769,7 +803,9 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -798,7 +834,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -807,7 +843,9 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -832,7 +870,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomType {}
 
             [Command]
@@ -843,7 +881,9 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -868,7 +908,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomType : IEnumerable<object>
             {
                 public IEnumerator<object> GetEnumerator() => Enumerable.Empty<object>().GetEnumerator();
@@ -884,7 +924,9 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -909,7 +951,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class ValidatorA : BindingValidator<int>
             {
                 public override BindingValidationError Validate(int value) => Ok();
@@ -917,7 +959,7 @@ public class ValidatorA : BindingValidator<int>
 
             public class ValidatorB : BindingValidator<int>
             {
-    public override BindingValidationError Validate(int value) => Error(""Hello world"");
+                public override BindingValidationError Validate(int value) => Error("Hello world");
             }
 
             [Command]
@@ -928,7 +970,9 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
@@ -953,14 +997,14 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public class CustomType
             {
                 public string Value { get; }
 
                 private CustomType(string value) => Value = value;
 
-    public static CustomType Parse(string value) => throw new Exception(""Hello world"");
+                public static CustomType Parse(string value) => throw new Exception("Hello world");
             }
 
             [Command]
@@ -971,7 +1015,9 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
+
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)

CliFx.Tests/DirectivesSpecs.cs

@@ -19,53 +19,35 @@ public class DirectivesSpecs : SpecsBase
     {
     }
 
-    [Fact]
+    [Fact(Timeout = 15000)]
     public async Task Debug_directive_can_be_specified_to_interrupt_execution_until_a_debugger_is_attached()
     {
         // Arrange
-        var stdOutBuffer = new StringBuilder();
+        using var cts = new CancellationTokenSource();
+
+        // We can't actually attach a debugger, but we can ensure that the process is waiting for one
+        void HandleStdOut(string line)
+        {
+            // Kill the process once it writes the output we expect
+            if (line.Contains("Attach debugger to", StringComparison.OrdinalIgnoreCase))
+                cts.Cancel();
+        }
 
         var command = Cli.Wrap("dotnet")
             .WithArguments(a => a
                 .Add(Dummy.Program.Location)
-                .Add("[debug]")) | stdOutBuffer;
+                .Add("[debug]")
+            ) | HandleStdOut;
 
-        // Act
+        // Act & assert
         try
         {
-            // This has a timeout just in case the execution hangs forever
-            using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(5));
-
-            var task = command.ExecuteAsync(cts.Token);
-
-            // We can't attach a debugger programmatically, so the application
-            // will hang indefinitely.
-            // To work around it, we will wait until the application writes
-            // something to the standard output and then kill it.
-            while (true)
+            await command.ExecuteAsync(cts.Token);
+        }
+        catch (OperationCanceledException ex) when (ex.CancellationToken == cts.Token)
         {
-                if (stdOutBuffer.Length > 0)
-                {
-                    cts.Cancel();
-                    break;
+            // This means that the process was killed after it wrote the expected output
         }
-
-                await Task.Delay(100, cts.Token);
-            }
-
-            await task;
-        }
-        catch (OperationCanceledException)
-        {
-            // It's expected to fail
-        }
-
-        var stdOut = stdOutBuffer.ToString();
-
-        // Assert
-        stdOut.Should().Contain("Attach debugger to");
-
-        TestOutput.WriteLine(stdOut);
     }
 
     [Fact]
@@ -74,13 +56,14 @@ public class DirectivesSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
-[Command(""cmd"")]
+            """
+            [Command("cmd")]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/EnvironmentSpecs.cs

@@ -25,11 +25,11 @@ public class EnvironmentSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", IsRequired = true, EnvironmentVariable = ""ENV_FOO"")]
+                [CommandOption("foo", IsRequired = true, EnvironmentVariable = "ENV_FOO")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -38,7 +38,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -67,11 +68,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", EnvironmentVariable = ""ENV_FOO"")]
+                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -80,7 +81,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -109,11 +111,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", EnvironmentVariable = ""ENV_FOO"")]
+                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
                 public IReadOnlyList<string> Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -124,7 +126,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -156,11 +159,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", EnvironmentVariable = ""ENV_FOO"")]
+                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -169,7 +172,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -198,11 +202,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", EnvironmentVariable = ""ENV_FOO"")]
+                [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -211,7 +215,8 @@ public class Command : ICommand
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -236,7 +241,7 @@ public class Command : ICommand
         stdOut.Trim().Should().Be("bar");
     }
 
-    [Fact]
+    [Fact(Timeout = 15000)]
     public async Task Environment_variables_are_extracted_automatically()
     {
         // Ensures that the environment variables are properly obtained from
@@ -246,9 +251,11 @@ public class Command : ICommand
         var command = Cli.Wrap("dotnet")
             .WithArguments(a => a
                 .Add(Dummy.Program.Location)
-                .Add("env-test"))
+                .Add("env-test")
+            )
             .WithEnvironmentVariables(e => e
-                .Set("ENV_TARGET", "Mars"));
+                .Set("ENV_TARGET", "Mars")
+            );
 
         // Act
         var result = await command.ExecuteBufferedAsync();

CliFx.Tests/ErrorReportingSpecs.cs

@@ -22,14 +22,15 @@ public class ErrorReportingSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) =>
-        throw new Exception(""Something went wrong"");
+                    throw new Exception("Something went wrong");
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -60,14 +61,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) =>
-        throw new Exception(""Something went wrong"", new Exception(""Another exception""));
+                    throw new Exception("Something went wrong", new Exception("Another exception"));
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -99,14 +101,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) =>
-        throw new CommandException(""Something went wrong"", 69);
+                    throw new CommandException("Something went wrong", 69);
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -134,14 +137,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) =>
-        throw new CommandException("""", 69);
+                    throw new CommandException("", 69);
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -172,14 +176,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) =>
-        throw new CommandException(""Something went wrong"", 69, true);
+                    throw new CommandException("Something went wrong", 69, true);
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/HelpTextSpecs.cs

@@ -44,13 +44,14 @@ public class HelpTextSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -77,19 +78,20 @@ public class DefaultCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
-[Command(""cmd"")]
+            """
+            [Command("cmd")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
 
-[Command(""cmd child"")]
+            [Command("cmd child")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -116,25 +118,26 @@ public class NamedChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
 
-[Command(""cmd"", Description = ""Description of a named command."")]
+            [Command("cmd", Description = "Description of a named command.")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
 
-[Command(""cmd child"")]
+            [Command("cmd child")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -160,25 +163,26 @@ public class NamedChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
 
-[Command(""cmd"")]
+            [Command("cmd")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
 
-[Command(""cmd child"", Description = ""Description of a named child command."")]
+            [Command("cmd child", Description = "Description of a named child command.")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console) => default;
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -257,13 +261,15 @@ public class NamedChildCommand : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
-[Command(Description = ""Description of the default command."")]
+            """
+                
+                [Command(Description = "Description of the default command.")]
                 public class DefaultCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -292,19 +298,21 @@ public class DefaultCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
+                
                 [Command]
                 public class DefaultCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd"")]
+                [Command("cmd")]
                 public class NamedCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -333,7 +341,8 @@ public class NamedCommand : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 [Command]
                 public class Command : ICommand
                 {
@@ -348,7 +357,8 @@ public class Command : ICommand
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -378,7 +388,8 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 // Base members appear last in reflection order
                 public abstract class CommandBase : ICommand
                 {
@@ -399,7 +410,8 @@ public class Command : CommandBase
                 
                     public override ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -428,22 +440,24 @@ public class Command : CommandBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 [Command]
                 public class Command : ICommand
                 {
-    [CommandOption(""foo"", IsRequired = true)]
+                    [CommandOption("foo", IsRequired = true)]
                     public string Foo { get; set; }
                 
-    [CommandOption(""bar"")]
+                    [CommandOption("bar")]
                     public string Bar { get; set; }
                 
-    [CommandOption(""baz"", IsRequired = true)]
+                    [CommandOption("baz", IsRequired = true)]
                     public IReadOnlyList<string> Baz { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -472,19 +486,21 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 [Command]
                 public class Command : ICommand
                 {
-    [CommandParameter(0, Name = ""foo"", Description = ""Description of foo."")]
+                    [CommandParameter(0, Name = "foo", Description = "Description of foo.")]
                     public string Foo { get; set; }
                 
-    [CommandOption(""bar"", Description = ""Description of bar."")]
+                    [CommandOption("bar", Description = "Description of bar.")]
                     public string Bar { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -515,13 +531,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 [Command]
                 public class Command : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -551,13 +569,15 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
-[Command(""cmd"")]
+            """
+                
+                [Command("cmd")]
                 public class Command : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -589,7 +609,8 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 public enum CustomEnum { One, Two, Three }
                 
                 [Command]
@@ -598,12 +619,13 @@ public class Command : ICommand
                     [CommandParameter(0)]
                     public CustomEnum Foo { get; set; }
                 
-    [CommandOption(""bar"")]
+                    [CommandOption("bar")]
                     public CustomEnum Bar { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -634,7 +656,8 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 public enum CustomEnum { One, Two, Three }
                 
                 [Command]
@@ -643,12 +666,13 @@ public class Command : ICommand
                     [CommandParameter(0)]
                     public IReadOnlyList<CustomEnum> Foo { get; set; }
                 
-    [CommandOption(""bar"")]
+                    [CommandOption("bar")]
                     public IReadOnlyList<CustomEnum> Bar { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -679,7 +703,8 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 public enum CustomEnum { One, Two, Three }
                 
                 [Command]
@@ -688,12 +713,13 @@ public class Command : ICommand
                     [CommandParameter(0)]
                     public CustomEnum? Foo { get; set; }
                 
-    [CommandOption(""bar"")]
+                    [CommandOption("bar")]
                     public IReadOnlyList<CustomEnum?> Bar { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -724,21 +750,23 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 public enum CustomEnum { One, Two, Three }
                 
                 [Command]
                 public class Command : ICommand
                 {
-    [CommandOption(""foo"", EnvironmentVariable = ""ENV_FOO"")]
+                    [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
                     public CustomEnum Foo { get; set; }
                 
-    [CommandOption(""bar"", EnvironmentVariable = ""ENV_BAR"")]
+                    [CommandOption("bar", EnvironmentVariable = "ENV_BAR")]
                     public CustomEnum Bar { get; set; }
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -768,39 +796,41 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+                
                 public enum CustomEnum { One, Two, Three }
                 
                 [Command]
                 public class Command : ICommand
                 {
-    [CommandOption(""foo"")]
+                    [CommandOption("foo")]
                     public object Foo { get; set; } = 42;
                 
-    [CommandOption(""bar"")]
-    public string Bar { get; set; } = ""hello"";
+                    [CommandOption("bar")]
+                    public string Bar { get; set; } = "hello";
                 
-    [CommandOption(""baz"")]
-    public IReadOnlyList<string> Baz { get; set; } = new[] {""one"", ""two"", ""three""};
+                    [CommandOption("baz")]
+                    public IReadOnlyList<string> Baz { get; set; } = new[] {"one", "two", "three"};
                 
-    [CommandOption(""qwe"")]
+                    [CommandOption("qwe")]
                     public bool Qwe { get; set; } = true;
                 
-    [CommandOption(""qop"")]
+                    [CommandOption("qop")]
                     public int? Qop { get; set; } = 1337;
                 
-    [CommandOption(""zor"")]
+                    [CommandOption("zor")]
                     public TimeSpan Zor { get; set; } = TimeSpan.FromMinutes(123);
                 
-    [CommandOption(""lol"")]
+                    [CommandOption("lol")]
                     public CustomEnum Lol { get; set; } = CustomEnum.Two;
                 
-    [CommandOption(""hmm"", IsRequired = true)]
-    public string Hmm { get; set; } = ""not printed"";
+                    [CommandOption("hmm", IsRequired = true)]
+                    public string Hmm { get; set; } = "not printed";
                 
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -836,25 +866,27 @@ public class Command : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
-[Command(""cmd1"", Description = ""Description of one command."")]
+            """
+                
+                [Command("cmd1", Description = "Description of one command.")]
                 public class FirstCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2"", Description = ""Description of another command."")]
+                [Command("cmd2", Description = "Description of another command.")]
                 public class SecondCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2 child"", Description = ""Description of another command's child command."")]
+                [Command("cmd2 child", Description = "Description of another command's child command.")]
                 public class SecondCommandChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -890,37 +922,39 @@ public class SecondCommandChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
-[Command(""cmd1"")]
+            """
+                
+                [Command("cmd1")]
                 public class FirstCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd1 child1"")]
+                [Command("cmd1 child1")]
                 public class FirstCommandFirstChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2"")]
+                [Command("cmd2")]
                 public class SecondCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2 child11"")]
+                [Command("cmd2 child11")]
                 public class SecondCommandFirstChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2 child2"")]
+                [Command("cmd2 child2")]
                 public class SecondCommandSecondChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -950,25 +984,27 @@ public class SecondCommandSecondChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
-[Command(""cmd1"")]
+            """
+                
+                [Command("cmd1")]
                 public class FirstCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2 child1"")]
+                [Command("cmd2 child1")]
                 public class SecondCommandFirstChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
                 
-[Command(""cmd2 child2"")]
+                [Command("cmd2 child2")]
                 public class SecondCommandSecondChildCommand : ICommand
                 {
                     public ValueTask ExecuteAsync(IConsole console) => default;
                 }
-");
+
+                """);
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)

CliFx.Tests/OptionBindingSpecs.cs

@@ -22,11 +22,11 @@ public class OptionBindingSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public bool Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -34,7 +34,9 @@ public class Command : ICommand
                     console.Output.WriteLine(Foo);
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -60,7 +62,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -72,7 +74,9 @@ public class Command : ICommand
                     console.Output.WriteLine(Foo);
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -98,24 +102,26 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
-    [CommandOption(""bar"")]
+                [CommandOption("bar")]
                 public string Bar { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -144,7 +150,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -156,12 +162,14 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -190,7 +198,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -202,12 +210,14 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -236,11 +246,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""Foo"")]
+                [CommandOption("Foo")]
                 public IReadOnlyList<string> Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -250,7 +260,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -280,7 +292,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -294,7 +306,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -324,11 +338,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public IReadOnlyList<string> Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -338,7 +352,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -368,7 +384,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -382,7 +398,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -412,11 +430,11 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", 'f')]
+                [CommandOption("foo", 'f')]
                 public IReadOnlyList<string> Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -426,7 +444,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -456,24 +476,26 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
-    [CommandOption(""bar"")]
-    public string Bar { get; set; } = ""hello"";
+                [CommandOption("bar")]
+                public string Bar { get; set; } = "hello";
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -502,7 +524,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             public static class SharedContext
             {
                 public static int Foo { get; set; }
@@ -512,7 +534,7 @@ public static class SharedContext
 
             public interface IHasFoo : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public int Foo
                 {
                     get => SharedContext.Foo;
@@ -522,7 +544,7 @@ public interface IHasFoo : ICommand
 
             public interface IHasBar : ICommand
             {
-    [CommandOption(""bar"")]
+                [CommandOption("bar")]
                 public bool Bar
                 {
                     get => SharedContext.Bar;
@@ -538,19 +560,20 @@ public interface IHasBaz : ICommand
             [Command]
             public class Command : IHasFoo, IHasBar, IHasBaz
             {
-    [CommandOption(""baz"")]
+                [CommandOption("baz")]
                 public string Baz { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + SharedContext.Foo);
-        console.Output.WriteLine(""Bar = "" + SharedContext.Bar);
-        console.Output.WriteLine(""Baz = "" + Baz);
+                    console.Output.WriteLine("Foo = " + SharedContext.Foo);
+                    console.Output.WriteLine("Bar = " + SharedContext.Bar);
+                    console.Output.WriteLine("Baz = " + Baz);
 
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -579,11 +602,11 @@ public class Command : IHasFoo, IHasBar, IHasBaz
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
@@ -592,7 +615,9 @@ public class Command : ICommand
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -618,15 +643,17 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", IsRequired = true)]
+                [CommandOption("foo", IsRequired = true)]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -652,15 +679,17 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", IsRequired = true)]
+                [CommandOption("foo", IsRequired = true)]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -686,15 +715,17 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"", IsRequired = true)]
+                [CommandOption("foo", IsRequired = true)]
                 public IReadOnlyList<string> Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -720,15 +751,17 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -754,15 +787,17 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
-    [CommandOption(""foo"")]
+                [CommandOption("foo")]
                 public string Foo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -781,4 +816,40 @@ public class Command : ICommand
         exitCode.Should().NotBe(0);
         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

@@ -21,7 +21,7 @@ public class ParameterBindingSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -33,12 +33,14 @@ public class Command : ICommand
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -67,7 +69,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -80,20 +82,22 @@ public class Command : ICommand
                 [CommandParameter(2)]
                 public IReadOnlyList<string> Baz { get; set; }
 
-    [CommandOption(""boo"")]
+                [CommandOption("boo")]
                 public string Boo { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     foreach (var i in Baz)
-            console.Output.WriteLine(""Baz = "" + i);
+                        console.Output.WriteLine("Baz = " + i);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -125,7 +129,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -133,16 +137,18 @@ public class Command : ICommand
                 public string Foo { get; set; }
 
                 [CommandParameter(1, IsRequired = false)]
-    public string Bar { get; set; } = ""xyz"";
+                public string Bar { get; set; } = "xyz";
 
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""Foo = "" + Foo);
-        console.Output.WriteLine(""Bar = "" + Bar);
+                    console.Output.WriteLine("Foo = " + Foo);
+                    console.Output.WriteLine("Bar = " + Bar);
 
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -171,7 +177,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -182,7 +188,9 @@ public class Command : ICommand
                 public string Bar { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -208,7 +216,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -219,7 +227,9 @@ public class Command : ICommand
                 public IReadOnlyList<string> Bar { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -245,7 +255,7 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -256,7 +266,9 @@ public class Command : ICommand
                 public string Bar { get; set; }
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/RoutingSpecs.cs

@@ -21,37 +21,38 @@ public class RoutingSpecs : SpecsBase
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""default"");
+                    console.Output.WriteLine("default");
                     return default;
                 }
             }
 
-[Command(""cmd"")]
+            [Command("cmd")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd"");
+                    console.Output.WriteLine("cmd");
                     return default;
                 }
             }
 
-[Command(""cmd child"")]
+            [Command("cmd child")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd child"");
+                    console.Output.WriteLine("cmd child");
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -77,37 +78,38 @@ public class NamedChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""default"");
+                    console.Output.WriteLine("default");
                     return default;
                 }
             }
 
-[Command(""cmd"")]
+            [Command("cmd")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd"");
+                    console.Output.WriteLine("cmd");
                     return default;
                 }
             }
 
-[Command(""cmd child"")]
+            [Command("cmd child")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd child"");
+                    console.Output.WriteLine("cmd child");
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)
@@ -133,37 +135,38 @@ public class NamedChildCommand : ICommand
         // Arrange
         var commandTypes = DynamicCommandBuilder.CompileMany(
             // language=cs
-            @"
+            """
             [Command]
             public class DefaultCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""default"");
+                    console.Output.WriteLine("default");
                     return default;
                 }
             }
 
-[Command(""cmd"")]
+            [Command("cmd")]
             public class NamedCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd"");
+                    console.Output.WriteLine("cmd");
                     return default;
                 }
             }
 
-[Command(""cmd child"")]
+            [Command("cmd child")]
             public class NamedChildCommand : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""cmd child"");
+                    console.Output.WriteLine("cmd child");
                     return default;
                 }
             }
-");
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommands(commandTypes)

CliFx.Tests/TypeActivationSpecs.cs

@@ -4,6 +4,7 @@ using System.Threading.Tasks;
 using CliFx.Infrastructure;
 using CliFx.Tests.Utils;
 using FluentAssertions;
+using Microsoft.Extensions.DependencyInjection;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -22,16 +23,18 @@ public class TypeActivationSpecs : SpecsBase
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""foo"");
+                    console.Output.WriteLine("foo");
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -58,14 +61,16 @@ public class Command : ICommand
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
                 public Command(string foo) {}
 
                 public ValueTask ExecuteAsync(IConsole console) => default;
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
@@ -87,12 +92,12 @@ public class Command : ICommand
     }
 
     [Fact]
-    public async Task Delegate_type_activator_can_initialize_a_type_using_a_custom_function()
+    public async Task Custom_type_activator_can_initialize_a_type_using_a_given_function()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
             [Command]
             public class Command : ICommand
             {
@@ -105,12 +110,14 @@ public class Command : ICommand
                     console.Output.WriteLine(_foo);
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)
             .UseConsole(FakeConsole)
-            .UseTypeActivator(type => Activator.CreateInstance(type, "hello world")!)
+            .UseTypeActivator(type => Activator.CreateInstance(type, "Hello world")!)
             .Build();
 
         // Act
@@ -123,25 +130,73 @@ public class Command : ICommand
 
         // Assert
         exitCode.Should().Be(0);
-        stdOut.Trim().Should().Be("hello world");
+        stdOut.Trim().Should().Be("Hello world");
     }
 
     [Fact]
-    public async Task Delegate_type_activator_fails_if_the_underlying_function_returns_null()
+    public async Task Custom_type_activator_can_initialize_a_type_using_a_service_provider()
     {
         // Arrange
         var commandType = DynamicCommandBuilder.Compile(
             // language=cs
-            @"
+            """
+            [Command]
+            public class Command : ICommand
+            {
+                private readonly string _foo;
+
+                public Command(string foo) => _foo = foo;
+
+                public ValueTask ExecuteAsync(IConsole console)
+                {
+                    console.Output.WriteLine(_foo);
+                    return default;
+                }
+            }
+            """
+        );
+
+        var serviceProvider = new ServiceCollection()
+            .AddSingleton(commandType, Activator.CreateInstance(commandType, "Hello world")!)
+            .BuildServiceProvider();
+
+        var application = new CliApplicationBuilder()
+            .AddCommand(commandType)
+            .UseConsole(FakeConsole)
+            .UseTypeActivator(serviceProvider)
+            .Build();
+
+        // Act
+        var exitCode = await application.RunAsync(
+            Array.Empty<string>(),
+            new Dictionary<string, string>()
+        );
+
+        var stdOut = FakeConsole.ReadOutputString();
+
+        // Assert
+        exitCode.Should().Be(0);
+        stdOut.Trim().Should().Be("Hello world");
+    }
+
+    [Fact]
+    public async Task Custom_type_activator_fails_if_the_underlying_function_returns_null()
+    {
+        // Arrange
+        var commandType = DynamicCommandBuilder.Compile(
+            // language=cs
+            """
             [Command]
             public class Command : ICommand
             {
                 public ValueTask ExecuteAsync(IConsole console)
                 {
-        console.Output.WriteLine(""foo"");
+                    console.Output.WriteLine("foo");
                     return default;
                 }
-}");
+            }
+            """
+        );
 
         var application = new CliApplicationBuilder()
             .AddCommand(commandType)

CliFx.Tests/Utils/DynamicCommandBuilder.cs

@@ -61,7 +61,7 @@ internal static class DynamicCommandBuilder
         var compilation = CSharpCompilation.Create(
             "CliFxTests_DynamicAssembly_" + Guid.NewGuid(),
             new[] {ast},
-            ReferenceAssemblies.Net50
+            Net70.References.All
                 .Append(MetadataReference.CreateFromFile(typeof(ICommand).Assembly.Location))
                 .Append(MetadataReference.CreateFromFile(typeof(DynamicCommandBuilder).Assembly.Location)),
             // DLL to avoid having to define the Main() method
@@ -76,9 +76,10 @@ internal static class DynamicCommandBuilder
         if (compilationErrors.Any())
         {
             throw new InvalidOperationException(
-                "Failed to compile code." +
-                Environment.NewLine +
-                string.Join(Environment.NewLine, compilationErrors.Select(e => e.ToString()))
+                $"""
+                Failed to compile code.
+                {string.Join(Environment.NewLine, compilationErrors.Select(e => e.ToString()))}
+                """
             );
         }
 
@@ -94,9 +95,10 @@ internal static class DynamicCommandBuilder
         if (emitErrors.Any())
         {
             throw new InvalidOperationException(
-                "Failed to emit code." +
-                Environment.NewLine +
-                string.Join(Environment.NewLine, emitErrors.Select(e => e.ToString()))
+                $"""
+                Failed to emit code.
+                {string.Join(Environment.NewLine, emitErrors.Select(e => e.ToString()))}
+                """
             );
         }
 

CliFx/Attributes/CommandOptionAttribute.cs

@@ -32,11 +32,15 @@ public sealed class CommandOptionAttribute : Attribute
     /// Whether this option is required (default: <c>false</c>).
     /// If an option is required, the user will get an error if they don't set it.
     /// </summary>
+    /// <remarks>
+    /// You can use the <c>required</c> keyword on the property (introduced in C# 11) to implicitly
+    /// set <see cref="IsRequired" /> to <c>true</c>.
+    /// </remarks>
     public bool IsRequired { get; set; }
 
     /// <summary>
     /// Environment variable whose value will be used as a fallback if the option
-    /// has not been explicitly set through command line arguments.
+    /// has not been explicitly set through command-line arguments.
     /// </summary>
     public string? EnvironmentVariable { get; set; }
 
@@ -47,7 +51,7 @@ public sealed class CommandOptionAttribute : Attribute
     public string? Description { get; set; }
 
     /// <summary>
-    /// Custom converter used for mapping the raw command line argument into
+    /// Custom converter used for mapping the raw command-line argument into
     /// a value expected by the underlying property.
     /// </summary>
     /// <remarks>

CliFx/Attributes/CommandParameterAttribute.cs

@@ -47,7 +47,7 @@ public sealed class CommandParameterAttribute : Attribute
     public string? Description { get; set; }
 
     /// <summary>
-    /// Custom converter used for mapping the raw command line argument into
+    /// Custom converter used for mapping the raw command-line argument into
     /// a value expected by the underlying property.
     /// </summary>
     /// <remarks>

CliFx/CliApplication.cs

@@ -2,6 +2,7 @@ using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
+using System.Runtime.InteropServices;
 using System.Threading.Tasks;
 using CliFx.Exceptions;
 using CliFx.Formatting;
@@ -14,7 +15,7 @@ using CliFx.Utils.Extensions;
 namespace CliFx;
 
 /// <summary>
-/// Command line application facade.
+/// Command-line application facade.
 /// </summary>
 public class CliApplication
 {
@@ -163,7 +164,7 @@ public class CliApplication
     }
 
     /// <summary>
-    /// Runs the application with the specified command line arguments and environment variables.
+    /// Runs the application with the specified command-line arguments and environment variables.
     /// Returns an exit code which indicates whether the application completed successfully.
     /// </summary>
     /// <remarks>
@@ -206,7 +207,7 @@ public class CliApplication
     }
 
     /// <summary>
-    /// Runs the application with the specified command line arguments.
+    /// Runs the application with the specified command-line arguments.
     /// Environment variables are resolved automatically.
     /// Returns an exit code which indicates whether the application completed successfully.
     /// </summary>
@@ -216,16 +217,18 @@ public class CliApplication
     /// </remarks>
     public async ValueTask<int> RunAsync(IReadOnlyList<string> commandLineArguments) => await RunAsync(
         commandLineArguments,
-        // Use case-sensitive comparison because environment variables are
-        // case-sensitive on Linux and macOS (but not on Windows).
         Environment
             .GetEnvironmentVariables()
-            .ToDictionary<string, string>(StringComparer.Ordinal)
+            .ToDictionary<string, string>(
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows)
+                    ? StringComparer.OrdinalIgnoreCase
+                    : StringComparer.Ordinal
+            )
     );
 
     /// <summary>
     /// Runs the application.
-    /// Command line arguments and environment variables are resolved automatically.
+    /// Command-line arguments and environment variables are resolved automatically.
     /// Returns an exit code which indicates whether the application completed successfully.
     /// </summary>
     /// <remarks>

CliFx/CliApplicationBuilder.cs

@@ -6,6 +6,7 @@ using System.Reflection;
 using CliFx.Attributes;
 using CliFx.Infrastructure;
 using CliFx.Schema;
+using CliFx.Utils;
 using CliFx.Utils.Extensions;
 
 namespace CliFx;
@@ -21,7 +22,7 @@ public partial class CliApplicationBuilder
     private bool _isPreviewModeAllowed = true;
     private string? _title;
     private string? _executableName;
-    private string? _versionText;
+    private string? _version;
     private string? _description;
     private IConsole? _console;
     private ITypeActivator? _typeActivator;
@@ -144,7 +145,7 @@ public partial class CliApplicationBuilder
     /// </remarks>
     public CliApplicationBuilder SetVersion(string version)
     {
-        _versionText = version;
+        _version = version;
         return this;
     }
 
@@ -181,6 +182,12 @@ public partial class CliApplicationBuilder
     public CliApplicationBuilder UseTypeActivator(Func<Type, object> typeActivator) =>
         UseTypeActivator(new DelegateTypeActivator(typeActivator));
 
+    /// <summary>
+    /// Configures the application to use the specified service provider for activating types.
+    /// </summary>
+    public CliApplicationBuilder UseTypeActivator(IServiceProvider serviceProvider) =>
+        UseTypeActivator(serviceProvider.GetService);
+
     /// <summary>
     /// Creates a configured instance of <see cref="CliApplication" />.
     /// </summary>
@@ -189,7 +196,7 @@ public partial class CliApplicationBuilder
         var metadata = new ApplicationMetadata(
             _title ?? GetDefaultTitle(),
             _executableName ?? GetDefaultExecutableName(),
-            _versionText ?? GetDefaultVersionText(),
+            _version ?? GetDefaultVersionText(),
             _description
         );
 
@@ -210,14 +217,9 @@ public partial class CliApplicationBuilder
 
 public partial class CliApplicationBuilder
 {
-    private static readonly Lazy<Assembly?> EntryAssemblyLazy = new(Assembly.GetEntryAssembly);
-
-    // Entry assembly can be null, for example in tests
-    private static Assembly? EntryAssembly => EntryAssemblyLazy.Value;
-
     private static string GetDefaultTitle()
     {
-        var entryAssemblyName = EntryAssembly?.GetName().Name;
+        var entryAssemblyName = EnvironmentEx.EntryAssembly?.GetName().Name;
         if (string.IsNullOrWhiteSpace(entryAssemblyName))
             return "App";
 
@@ -226,26 +228,39 @@ public partial class CliApplicationBuilder
 
     private static string GetDefaultExecutableName()
     {
-        var entryAssemblyLocation = EntryAssembly?.Location;
+        var entryAssemblyLocation = EnvironmentEx.EntryAssembly?.Location;
         if (string.IsNullOrWhiteSpace(entryAssemblyLocation))
             return "app";
 
-        // The assembly can be an .exe or a .dll, depending on how it was packaged
+        // If the application was launched via matching EXE apphost, use that as the executable name
+        var isLaunchedViaAppHost = string.Equals(
+            EnvironmentEx.ProcessPath,
+            Path.ChangeExtension(entryAssemblyLocation, ".exe"),
+            StringComparison.OrdinalIgnoreCase
+        );
+
+        if (isLaunchedViaAppHost)
+            return Path.GetFileNameWithoutExtension(entryAssemblyLocation);
+
+        // Otherwise, use the entry assembly as the executable name.
+        // Prefix it with `dotnet` if it's a DLL file.
         var isDll = string.Equals(
             Path.GetExtension(entryAssemblyLocation),
             ".dll",
             StringComparison.OrdinalIgnoreCase
         );
 
-        var name = isDll
+        return isDll
             ? "dotnet " + Path.GetFileName(entryAssemblyLocation)
             : Path.GetFileNameWithoutExtension(entryAssemblyLocation);
-
-        return name;
     }
 
-    private static string GetDefaultVersionText() =>
-        EntryAssembly is not null
-            ? "v" + EntryAssembly.GetName().Version.ToSemanticString()
-            : "v1.0";
+    private static string GetDefaultVersionText()
+    {
+        var entryAssemblyVersion = EnvironmentEx.EntryAssembly?.GetName().Version;
+        if (entryAssemblyVersion is null)
+            return "v1.0";
+
+        return "v" + entryAssemblyVersion.ToSemanticString();
+    }
 }

CliFx/CliFx.csproj

@@ -1,10 +1,13 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.1;netstandard2.0</TargetFrameworks>
-    <Authors>$(Company)</Authors>
-    <Description>Declarative framework for building command line applications</Description>
+    <TargetFrameworks>netstandard2.0;netstandard2.1</TargetFrameworks>
     <IsPackable>true</IsPackable>
+  </PropertyGroup>
+
+  <PropertyGroup>
+    <Authors>$(Company)</Authors>
+    <Description>Class-first framework for building command-line interfaces</Description>
     <PackageTags>command line executable interface framework parser arguments cli app application net core</PackageTags>
     <PackageProjectUrl>https://github.com/Tyrrrz/CliFx</PackageProjectUrl>
     <PackageReleaseNotes>https://github.com/Tyrrrz/CliFx/blob/master/Changelog.md</PackageReleaseNotes>
@@ -24,16 +27,14 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="all" />
-    <PackageReference Include="Nullable" Version="1.3.0" PrivateAssets="all" />
+    <PackageReference Include="PolyShim" Version="1.1.0" PrivateAssets="all" />
+    <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" Condition="'$(TargetFramework)' == 'netstandard2.0'" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
-    <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
-  </ItemGroup>
-
-  <!-- Pack the analyzer assembly inside the package -->
+  <!-- Embed the analyzer inside the package -->
   <ItemGroup>
     <ProjectReference Include="../CliFx.Analyzers/CliFx.Analyzers.csproj" ReferenceOutputAssembly="false" OutputItemType="analyzer" />
+    <None Include="../CliFx.Analyzers/bin/$(Configuration)/netstandard2.0/CliFx.Analyzers.deps.json" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
     <None Include="../CliFx.Analyzers/bin/$(Configuration)/netstandard2.0/CliFx.Analyzers.dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
     <None Include="../CliFx.Analyzers/bin/$(Configuration)/netstandard2.0/System.Buffers.dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />
     <None Include="../CliFx.Analyzers/bin/$(Configuration)/netstandard2.0/System.Collections.Immutable.dll" Pack="true" PackagePath="analyzers/dotnet/cs" Visible="false" />

CliFx/CommandBinder.cs

@@ -31,7 +31,7 @@ internal class CommandBinder
             return converter.Convert(rawValue);
         }
 
-        // Assignable from string (e.g. string itself, object, etc)
+        // Assignable from a string (e.g. string itself, object, etc)
         if (targetType.IsAssignableFrom(typeof(string)))
         {
             return rawValue;
@@ -77,7 +77,7 @@ internal class CommandBinder
                 : null;
         }
 
-        // String-constructible (FileInfo, etc)
+        // String-constructable (FileInfo, etc)
         var stringConstructor = targetType.GetConstructor(new[] { typeof(string) });
         if (stringConstructor is not null)
         {
@@ -99,11 +99,11 @@ internal class CommandBinder
         }
 
         throw CliFxException.InternalError(
-            $"{memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has an unsupported underlying property type." +
-            Environment.NewLine +
-            $"There is no known way to convert a string value into an instance of type `{targetType.FullName}`." +
-            Environment.NewLine +
-            "To fix this, either change the property to use a supported type or configure a custom converter."
+            $"""
+            {memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has an unsupported underlying property type.
+            There is no known way to convert a string value into an instance of type `{targetType.FullName}`
+            To fix this, either change the property to use a supported type or configure a custom converter.
+            """
         );
     }
 
@@ -125,7 +125,7 @@ internal class CommandBinder
             return array;
         }
 
-        // Array-constructible (List<T>, HashSet<T>, etc)
+        // Array-constructable (List<T>, HashSet<T>, etc)
         var arrayConstructor = targetEnumerableType.GetConstructor(new[] { arrayType });
         if (arrayConstructor is not null)
         {
@@ -133,11 +133,11 @@ internal class CommandBinder
         }
 
         throw CliFxException.InternalError(
-            $"{memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has an unsupported underlying property type." +
-            Environment.NewLine +
-            $"There is no known way to convert an array of `{targetElementType.FullName}` into an instance of type `{targetEnumerableType.FullName}`." +
-            Environment.NewLine +
-            "To fix this, change the property to use a type which can be assigned from an array or a type that has a constructor which accepts an array."
+            $"""
+            {memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has an unsupported underlying property type.
+            There is no known way to convert an array of `{targetElementType.FullName}` into an instance of type `{targetEnumerableType.FullName}`.
+            To fix this, change the property to use a type which can be assigned from an array or a type that has a constructor which accepts an array.
+            """
         );
     }
 
@@ -169,20 +169,21 @@ internal class CommandBinder
                 : ex.Message;
 
             throw CliFxException.UserError(
-                $"{memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} cannot be set from provided argument(s):" +
-                Environment.NewLine +
-                rawValues.Select(v => '<' + v + '>').JoinToString(" ") +
-                Environment.NewLine +
-                $"Error: {errorMessage}",
+                $"""
+                {memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} cannot be set from the provided argument(s):
+                {rawValues.Select(v => '<' + v + '>').JoinToString(" ")}
+                Error: {errorMessage}
+                """,
                 ex
             );
         }
 
         // Mismatch (scalar but too many values)
         throw CliFxException.UserError(
-            $"{memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} expects a single argument, but provided with multiple:" +
-            Environment.NewLine +
-            rawValues.Select(v => '<' + v + '>').JoinToString(" ")
+            $"""
+            {memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} expects a single argument, but provided with multiple:
+            {rawValues.Select(v => '<' + v + '>').JoinToString(" ")}
+            """
         );
     }
 
@@ -202,11 +203,11 @@ internal class CommandBinder
         if (errors.Any())
         {
             throw CliFxException.UserError(
-                $"{memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has been provided with an invalid value." +
-                Environment.NewLine +
-                "Error(s):" +
-                Environment.NewLine +
-                errors.Select(e => "- " + e.Message).JoinToString(Environment.NewLine)
+                $"""
+                {memberSchema.GetKind()} {memberSchema.GetFormattedIdentifier()} has been provided with an invalid value.
+                Error(s):
+                {errors.Select(e => "- " + e.Message).JoinToString(Environment.NewLine)}
+                """
             );
         }
     }
@@ -264,22 +265,20 @@ internal class CommandBinder
         if (remainingParameterInputs.Any())
         {
             throw CliFxException.UserError(
-                "Unexpected parameter(s):" +
-                Environment.NewLine +
-                remainingParameterInputs
-                    .Select(p => p.GetFormattedIdentifier())
-                    .JoinToString(" ")
+                $"""
+                Unexpected parameter(s):
+                {remainingParameterInputs.Select(p => p.GetFormattedIdentifier()).JoinToString(" ")}
+                """
             );
         }
 
         if (remainingRequiredParameterSchemas.Any())
         {
             throw CliFxException.UserError(
-                "Missing required parameter(s):" +
-                Environment.NewLine +
-                remainingRequiredParameterSchemas
-                    .Select(p => p.GetFormattedIdentifier())
-                    .JoinToString(" ")
+                $"""
+                Missing required parameter(s):
+                {remainingRequiredParameterSchemas.Select(p => p.GetFormattedIdentifier()).JoinToString(" ")}
+                """
             );
         }
     }
@@ -308,7 +307,7 @@ internal class CommandBinder
 
                 BindMember(optionSchema, commandInstance, rawValues);
 
-                // Required options require at least one value to be set
+                // Required options need at least one value to be set
                 if (rawValues.Any())
                     remainingRequiredOptionSchemas.Remove(optionSchema);
             }
@@ -321,7 +320,7 @@ internal class CommandBinder
 
                 BindMember(optionSchema, commandInstance, rawValues);
 
-                // Required options require at least one value to be set
+                // Required options need at least one value to be set
                 if (rawValues.Any())
                     remainingRequiredOptionSchemas.Remove(optionSchema);
             }
@@ -337,22 +336,20 @@ internal class CommandBinder
         if (remainingOptionInputs.Any())
         {
             throw CliFxException.UserError(
-                "Unrecognized option(s):" +
-                Environment.NewLine +
-                remainingOptionInputs
-                    .Select(o => o.GetFormattedIdentifier())
-                    .JoinToString(", ")
+                $"""
+                Unrecognized option(s):
+                {remainingOptionInputs.Select(o => o.GetFormattedIdentifier()).JoinToString(", ")}
+                """
             );
         }
 
         if (remainingRequiredOptionSchemas.Any())
         {
             throw CliFxException.UserError(
-                "Missing required option(s):" +
-                Environment.NewLine +
-                remainingRequiredOptionSchemas
-                    .Select(o => o.GetFormattedIdentifier())
-                    .JoinToString(", ")
+                $"""
+                Missing required option(s):
+                {remainingRequiredOptionSchemas.Select(o => o.GetFormattedIdentifier()).JoinToString(", ")}
+                """
             );
         }
     }

CliFx/Extensibility/BindingConverter.cs

@@ -12,7 +12,7 @@ internal interface IBindingConverter
 public abstract class BindingConverter<T> : IBindingConverter
 {
     /// <summary>
-    /// Parses value from a raw command line argument.
+    /// Parses value from a raw command-line argument.
     /// </summary>
     public abstract T Convert(string? rawValue);
 

CliFx/Formatting/CommandInputConsoleFormatter.cs

@@ -13,7 +13,7 @@ internal class CommandInputConsoleFormatter : ConsoleFormatter
 
     private void WriteCommandLineArguments(CommandInput commandInput)
     {
-        Write("Command line:");
+        Write("Command-line:");
         WriteLine();
 
         WriteHorizontalMargin();

CliFx/Formatting/HelpConsoleFormatter.cs

@@ -367,7 +367,9 @@ internal class HelpConsoleFormatter : ConsoleFormatter
     {
         var childCommandSchemas = _context
             .ApplicationSchema
-            .GetChildCommands(_context.CommandSchema.Name);
+            .GetChildCommands(_context.CommandSchema.Name)
+            .OrderBy(a => a.Name, StringComparer.Ordinal)
+            .ToArray();
 
         if (!childCommandSchemas.Any())
             return;
@@ -402,7 +404,9 @@ internal class HelpConsoleFormatter : ConsoleFormatter
             // Child commands of child command
             var grandChildCommandSchemas = _context
                 .ApplicationSchema
-                .GetChildCommands(childCommandSchema.Name);
+                .GetChildCommands(childCommandSchema.Name)
+                .OrderBy(c => c.Name, StringComparer.Ordinal)
+                .ToArray();
 
             if (grandChildCommandSchemas.Any())
             {

CliFx/ICommand.cs

@@ -4,7 +4,7 @@ using CliFx.Infrastructure;
 namespace CliFx;
 
 /// <summary>
-/// Entry point through which the user interacts with the command line application.
+/// Entry point through which the user interacts with the command-line application.
 /// </summary>
 public interface ICommand
 {

CliFx/Infrastructure/ConsoleReader.cs

@@ -99,10 +99,8 @@ public partial class ConsoleReader : StreamReader
 
 public partial class ConsoleReader
 {
-    internal static ConsoleReader Create(IConsole console, Stream? stream) => new(
+    internal static ConsoleReader Create(IConsole console, Stream stream) => new(
         console,
-        stream is not null
-            ? Stream.Synchronized(stream)
-            : Stream.Null
+        Stream.Synchronized(stream)
     );
 }

CliFx/Infrastructure/ConsoleWriter.cs

@@ -272,10 +272,8 @@ public partial class ConsoleWriter : StreamWriter
 
 public partial class ConsoleWriter
 {
-    internal static ConsoleWriter Create(IConsole console, Stream? stream) => new(
+    internal static ConsoleWriter Create(IConsole console, Stream stream) => new(
         console,
-        stream is not null
-            ? Stream.Synchronized(stream)
-            : Stream.Null
+        Stream.Synchronized(stream)
     ) {AutoFlush = true};
 }

CliFx/Infrastructure/DefaultTypeActivator.cs

@@ -20,11 +20,11 @@ public class DefaultTypeActivator : ITypeActivator
         catch (MemberAccessException ex)
         {
             throw CliFxException.InternalError(
-                $"Failed to create an instance of type `{type.FullName}`, could not access the constructor." +
-                Environment.NewLine +
-                "Default type activator is only capable of instantiating a type if it has a public parameterless constructor." +
-                Environment.NewLine +
-                "To fix this, either add a parameterless constructor to the type or configure a custom activator for the application.",
+                $"""
+                Failed to create an instance of type `{type.FullName}`, could not access the constructor.
+                Default type activator is only capable of instantiating a type if it has a public parameterless constructor.
+                To fix this, either add a parameterless constructor to the type or configure a custom activator for the application.
+                """,
                 ex
             );
         }

CliFx/Infrastructure/DelegateTypeActivator.cs

@@ -24,11 +24,11 @@ public class DelegateTypeActivator : ITypeActivator
         if (instance is null)
         {
             throw CliFxException.InternalError(
-                $"Failed to create an instance of type `{type.FullName}`, received <null> instead." +
-                Environment.NewLine +
-                "To fix this, ensure that the provided type activator is configured correctly, as it's not expected to return <null>." +
-                Environment.NewLine +
-                "If you are relying on a dependency container, this error may indicate that the specified type has not been registered."
+                $"""
+                Failed to create an instance of type `{type.FullName}`, received <null> instead.
+                To fix this, ensure that the provided type activator is configured correctly, as it's not expected to return <null>.
+                If you are relying on a dependency container, this error may indicate that the specified type has not been registered.
+                """
             );
         }
 

CliFx/Infrastructure/FakeConsole.cs

@@ -42,11 +42,10 @@ public class FakeConsole : IConsole, IDisposable
     public ConsoleColor BackgroundColor { get; set; } = ConsoleColor.Black;
 
     /// <inheritdoc />
-    public void ResetColor()
-    {
-        ForegroundColor = ConsoleColor.Gray;
-        BackgroundColor = ConsoleColor.Black;
-    }
+    public int WindowWidth { get; set; } = 232; // Windows defaults
+
+    /// <inheritdoc />
+    public int WindowHeight { get; set; } = 14; // Windows defaults
 
     /// <inheritdoc />
     public int CursorLeft { get; set; }
@@ -59,9 +58,35 @@ public class FakeConsole : IConsole, IDisposable
     /// </summary>
     public FakeConsole(Stream? input = null, Stream? output = null, Stream? error = null)
     {
-        Input = ConsoleReader.Create(this, input);
-        Output = ConsoleWriter.Create(this, output);
-        Error = ConsoleWriter.Create(this, error);
+        Input = ConsoleReader.Create(this, input ?? Stream.Null);
+        Output = ConsoleWriter.Create(this, output ?? Stream.Null);
+        Error = ConsoleWriter.Create(this, error ?? Stream.Null);
+    }
+
+    /// <inheritdoc />
+    public ConsoleKeyInfo ReadKey(bool intercept = false) =>
+        _keys.TryDequeue(out var key)
+            ? key
+            : throw new InvalidOperationException(
+                "Cannot read key because there are no key presses enqueued. " +
+                $"Use the `{nameof(EnqueueKey)}(...)` method to simulate a key press."
+            );
+
+    /// <summary>
+    /// Enqueues a simulated key press, which can then be read by calling <see cref="ReadKey" />.
+    /// </summary>
+    public void EnqueueKey(ConsoleKeyInfo key) => _keys.Enqueue(key);
+
+    /// <inheritdoc />
+    public void ResetColor()
+    {
+        ForegroundColor = ConsoleColor.Gray;
+        BackgroundColor = ConsoleColor.Black;
+    }
+
+    /// <inheritdoc />
+    public void Clear()
+    {
     }
 
     /// <inheritdoc />
@@ -87,25 +112,6 @@ public class FakeConsole : IConsole, IDisposable
         }
     }
 
-    /// <inheritdoc />
-    public void Clear()
-    {
-    }
-
-    /// <inheritdoc />
-    public ConsoleKeyInfo ReadKey(bool intercept = false) =>
-        _keys.TryDequeue(out var key)
-            ? key
-            : throw new InvalidOperationException(
-                "Cannot read key because there are no key presses enqueued. " +
-                $"Use the `{nameof(EnqueueKey)}(...)` method to simulate a key press."
-            );
-
-    /// <summary>
-    /// Enqueues a simulated key press, which can then be read by calling <see cref="ReadKey"/>.
-    /// </summary>
-    public void EnqueueKey(ConsoleKeyInfo key) => _keys.Enqueue(key);
-
     /// <inheritdoc />
     public virtual void Dispose() => _cancellationTokenSource.Dispose();
 }

CliFx/Infrastructure/IConsole.cs

@@ -15,7 +15,7 @@ public interface IConsole
     ConsoleReader Input { get; }
 
     /// <summary>
-    /// Whether the input stream is redirected.
+    /// Gets a value that indicates whether input has been redirected from the standard input stream.
     /// </summary>
     bool IsInputRedirected { get; }
 
@@ -25,7 +25,7 @@ public interface IConsole
     ConsoleWriter Output { get; }
 
     /// <summary>
-    /// Whether the output stream is redirected.
+    /// Gets a value that indicates whether output has been redirected from the standard output stream.
     /// </summary>
     bool IsOutputRedirected { get; }
 
@@ -35,39 +35,59 @@ public interface IConsole
     ConsoleWriter Error { get; }
 
     /// <summary>
-    /// Whether the error stream is redirected.
+    /// Gets a value that indicates whether error output has been redirected from the standard error stream.
     /// </summary>
     bool IsErrorRedirected { get; }
 
     /// <summary>
-    /// Current foreground color.
+    /// Gets or sets the foreground color of the console
     /// </summary>
     ConsoleColor ForegroundColor { get; set; }
 
     /// <summary>
-    /// Current background color.
+    /// Gets or sets the background color of the console.
     /// </summary>
     ConsoleColor BackgroundColor { get; set; }
 
     /// <summary>
-    /// Resets foreground and background colors to their default values.
+    /// Gets or sets the width of the console window.
     /// </summary>
-    void ResetColor();
+    int WindowWidth { get; set; }
 
     /// <summary>
-    /// Cursor left offset.
+    /// Gets or sets the height of the console window.
+    /// </summary>
+    int WindowHeight { get; set; }
+
+    /// <summary>
+    /// Gets or sets the column position of the cursor within the buffer area.
     /// </summary>
     int CursorLeft { get; set; }
 
     /// <summary>
-    /// Cursor top offset.
+    /// Gets or sets the row position of the cursor within the buffer area.
     /// </summary>
     int CursorTop { get; set; }
 
+    /// <summary>
+    /// Obtains the next character or function key pressed by the user.
+    /// </summary>
+    ConsoleKeyInfo ReadKey(bool intercept = false);
+
+    /// <summary>
+    /// Sets the foreground and background console colors to their defaults.
+    /// </summary>
+    void ResetColor();
+
+    /// <summary>
+    /// Clears the console buffer and corresponding console window of display information.
+    /// </summary>
+    void Clear();
+
     /// <summary>
     /// Registers a handler for the interrupt signal (Ctrl+C) on the console and returns
     /// a token representing the cancellation request.
-    /// Subsequent calls to this method have no side-effects and return the same token.
+    /// Subsequent calls to this method have no side effects and return the same token.
     /// </summary>
     /// <remarks>
     /// <para>
@@ -82,16 +102,6 @@ public interface IConsole
     /// </para>
     /// </remarks>
     CancellationToken RegisterCancellationHandler();
-
-    /// <summary>
-    /// Clears the console buffer and corresponding console window of display information.
-    /// </summary>
-    void Clear();
-
-    /// <summary>
-    /// Obtains the next character or function key pressed by the user.
-    /// </summary>
-    ConsoleKeyInfo ReadKey(bool intercept = false);
 }
 
 /// <summary>

CliFx/Infrastructure/SystemConsole.cs

@@ -42,18 +42,19 @@ public class SystemConsole : IConsole, IDisposable
         set => Console.BackgroundColor = value;
     }
 
-    /// <summary>
-    /// Initializes an instance of <see cref="SystemConsole"/>.
-    /// </summary>
-    public SystemConsole()
+    /// <inheritdoc />
+    public int WindowWidth
     {
-        Input = ConsoleReader.Create(this, Console.OpenStandardInput());
-        Output = ConsoleWriter.Create(this, Console.OpenStandardOutput());
-        Error = ConsoleWriter.Create(this, Console.OpenStandardError());
+        get => Console.WindowWidth;
+        set => Console.WindowWidth = value;
     }
 
     /// <inheritdoc />
-    public void ResetColor() => Console.ResetColor();
+    public int WindowHeight
+    {
+        get => Console.WindowHeight;
+        set => Console.WindowHeight = value;
+    }
 
     /// <inheritdoc />
     public int CursorLeft
@@ -69,6 +70,25 @@ public class SystemConsole : IConsole, IDisposable
         set => Console.CursorTop = value;
     }
 
+    /// <summary>
+    /// Initializes an instance of <see cref="SystemConsole" />.
+    /// </summary>
+    public SystemConsole()
+    {
+        Input = ConsoleReader.Create(this, Console.OpenStandardInput());
+        Output = ConsoleWriter.Create(this, Console.OpenStandardOutput());
+        Error = ConsoleWriter.Create(this, Console.OpenStandardError());
+    }
+
+    /// <inheritdoc />
+    public ConsoleKeyInfo ReadKey(bool intercept = false) => Console.ReadKey(intercept);
+
+    /// <inheritdoc />
+    public void ResetColor() => Console.ResetColor();
+
+    /// <inheritdoc />
+    public void Clear() => Console.Clear();
+
     /// <inheritdoc />
     public CancellationToken RegisterCancellationHandler()
     {
@@ -90,12 +110,6 @@ public class SystemConsole : IConsole, IDisposable
         return (_cancellationTokenSource = cts).Token;
     }
 
-    /// <inheritdoc />
-    public void Clear() => Console.Clear();
-
-    /// <inheritdoc />
-    public ConsoleKeyInfo ReadKey(bool intercept = false) => Console.ReadKey(intercept);
-
     /// <inheritdoc />
     public void Dispose()
     {

CliFx/Input/CommandInput.cs

@@ -1,7 +1,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 using CliFx.Utils.Extensions;
 
 namespace CliFx.Input;
@@ -154,7 +153,7 @@ internal partial class CommandInput
                 if (!string.IsNullOrWhiteSpace(lastOptionIdentifier))
                     result.Add(new OptionInput(lastOptionIdentifier, lastOptionValues));
 
-                lastOptionIdentifier = argument.Substring(2);
+                lastOptionIdentifier = argument[2..];
                 lastOptionValues = new List<string>();
             }
             // Short name
@@ -162,7 +161,7 @@ internal partial class CommandInput
                      argument.Length > 1 &&
                      char.IsLetter(argument[1]))
             {
-                foreach (var alias in argument.Substring(1))
+                foreach (var alias in argument[1..])
                 {
                     // Flush previous
                     if (!string.IsNullOrWhiteSpace(lastOptionIdentifier))

CliFx/Schema/CommandSchema.cs

@@ -70,8 +70,7 @@ internal partial class CommandSchema
     public static bool IsCommandType(Type type) =>
         type.Implements(typeof(ICommand)) &&
         type.IsDefined(typeof(CommandAttribute)) &&
-        !type.IsAbstract &&
-        !type.IsInterface;
+        type is { IsAbstract: false, IsInterface: false };
 
     public static CommandSchema? TryResolve(Type type)
     {
@@ -88,7 +87,7 @@ internal partial class CommandSchema
             : new[] {OptionSchema.HelpOption};
 
         var properties = type
-            // Get properties directly on command type
+            // Get properties directly on the command type
             .GetProperties()
             // Get non-abstract properties on interfaces (to support default interfaces members)
             .Union(type
@@ -129,15 +128,13 @@ internal partial class CommandSchema
         if (schema is null)
         {
             throw CliFxException.InternalError(
-                $"Type `{type.FullName}` is not a valid command type." +
-                Environment.NewLine +
-                "In order to be a valid command type, it must:" +
-                Environment.NewLine +
-                $"- Implement `{typeof(ICommand).FullName}`" +
-                Environment.NewLine +
-                $"- Be annotated with `{typeof(CommandAttribute).FullName}`" +
-                Environment.NewLine +
-                "- Not be an abstract class"
+                $"""
+                Type `{type.FullName}` is not a valid command type.
+                In order to be a valid command type, it must:
+                - Implement `{typeof(ICommand).FullName}`
+                - Be annotated with `{typeof(CommandAttribute).FullName}`
+                - Not be an abstract class
+                """
             );
         }
 

CliFx/Schema/OptionSchema.cs

@@ -3,6 +3,7 @@ using System.Collections.Generic;
 using System.Reflection;
 using System.Text;
 using CliFx.Attributes;
+using CliFx.Utils.Extensions;
 
 namespace CliFx.Schema;
 
@@ -101,6 +102,7 @@ internal partial class OptionSchema
         // The user may mistakenly specify dashes, thinking it's required, so trim them
         var name = attribute.Name?.TrimStart('-').Trim();
         var environmentVariable = attribute.EnvironmentVariable?.Trim();
+        var isRequired = attribute.IsRequired || property.IsRequired();
         var description = attribute.Description?.Trim();
 
         return new OptionSchema(
@@ -108,7 +110,7 @@ internal partial class OptionSchema
             name,
             attribute.ShortName,
             environmentVariable,
-            attribute.IsRequired,
+            isRequired,
             description,
             attribute.Converter,
             attribute.Validators

CliFx/Schema/ParameterSchema.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Reflection;
 using CliFx.Attributes;
+using CliFx.Utils.Extensions;
 
 namespace CliFx.Schema;
 
@@ -53,13 +54,14 @@ internal partial class ParameterSchema
             return null;
 
         var name = attribute.Name?.Trim() ?? property.Name.ToLowerInvariant();
+        var isRequired = attribute.IsRequired || property.IsRequired();
         var description = attribute.Description?.Trim();
 
         return new ParameterSchema(
             new BindablePropertyDescriptor(property),
             attribute.Order,
             name,
-            attribute.IsRequired,
+            isRequired,
             description,
             attribute.Converter,
             attribute.Validators

CliFx/Utils/EnvironmentEx.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Diagnostics;
+using System.Reflection;
+
+namespace CliFx.Utils;
+
+internal static class EnvironmentEx
+{
+    private static readonly Lazy<string?> ProcessPathLazy = new(() =>
+    {
+        using var process = Process.GetCurrentProcess();
+        return process.MainModule?.FileName;
+    });
+
+    public static string? ProcessPath => ProcessPathLazy.Value;
+
+    private static readonly Lazy<Assembly?> EntryAssemblyLazy = new(Assembly.GetEntryAssembly);
+
+    public static Assembly? EntryAssembly => EntryAssemblyLazy.Value;
+}

CliFx/Utils/Extensions/CollectionExtensions.cs

@@ -1,4 +1,5 @@
-using System.Collections;
+using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 
@@ -37,4 +38,14 @@ internal static class CollectionExtensions
         dictionary
             .Cast<DictionaryEntry>()
             .ToDictionary(entry => (TKey) entry.Key, entry => (TValue) entry.Value, comparer);
+
+    public static Array ToNonGenericArray<T>(this IEnumerable<T> source, Type elementType)
+    {
+        var sourceAsCollection = source as ICollection ?? source.ToArray();
+
+        var array = Array.CreateInstance(elementType, sourceAsCollection.Count);
+        sourceAsCollection.CopyTo(array, 0);
+
+        return array;
+    }
 }

CliFx/Utils/Extensions/PropertyExtensions.cs

@@ -0,0 +1,18 @@
+using System;
+using System.Linq;
+using System.Reflection;
+
+namespace CliFx.Utils.Extensions;
+
+internal static class PropertyExtensions
+{
+    public static bool IsRequired(this PropertyInfo propertyInfo) =>
+        // Match attribute by name to avoid depending on .NET 7.0+ and to allow polyfilling
+        propertyInfo.GetCustomAttributes().Any(a =>
+            string.Equals(
+                a.GetType().FullName,
+                "System.Runtime.CompilerServices.RequiredMemberAttribute",
+                StringComparison.Ordinal
+            )
+        );
+}

CliFx/Utils/Extensions/TypeExtensions.cs

@@ -11,7 +11,8 @@ internal static class TypeExtensions
     public static bool Implements(this Type type, Type interfaceType) =>
         type.GetInterfaces().Contains(interfaceType);
 
-    public static Type? TryGetNullableUnderlyingType(this Type type) => Nullable.GetUnderlyingType(type);
+    public static Type? TryGetNullableUnderlyingType(this Type type) =>
+        Nullable.GetUnderlyingType(type);
 
     public static Type? TryGetEnumerableUnderlyingType(this Type type)
     {
@@ -44,16 +45,6 @@ internal static class TypeExtensions
         );
     }
 
-    public static Array ToNonGenericArray<T>(this IEnumerable<T> source, Type elementType)
-    {
-        var sourceAsCollection = source as ICollection ?? source.ToArray();
-
-        var array = Array.CreateInstance(elementType, sourceAsCollection.Count);
-        sourceAsCollection.CopyTo(array, 0);
-
-        return array;
-    }
-
     public static bool IsToStringOverriden(this Type type)
     {
         var toStringMethod = type.GetMethod(nameof(ToString), Type.EmptyTypes);

CliFx/Utils/Polyfills.Collections.cs

@@ -1,26 +0,0 @@
-// ReSharper disable CheckNamespace
-
-#if NETSTANDARD2_0
-using System.Collections.Generic;
-
-internal static class CollectionPolyfills
-{
-    public static void Deconstruct<TKey, TValue>(this KeyValuePair<TKey, TValue> pair, out TKey key, out TValue value)
-    {
-        key = pair.Key;
-        value = pair.Value;
-    }
-
-    public static TValue GetValueOrDefault<TKey, TValue>(this IReadOnlyDictionary<TKey, TValue> dic, TKey key) =>
-        dic.TryGetValue(key!, out var result) ? result! : default!;
-}
-
-namespace System.Linq
-{
-    internal static class LinqPolyfills
-    {
-        public static HashSet<T> ToHashSet<T>(this IEnumerable<T> source, IEqualityComparer<T> comparer) =>
-            new(source, comparer);
-    }
-}
-#endif

CliFx/Utils/Polyfills.Streams.cs

@@ -1,11 +0,0 @@
-// ReSharper disable CheckNamespace
-
-#if NETSTANDARD2_0
-using System.IO;
-
-internal static class StreamPolyfills
-{
-    public static void Write(this Stream stream, byte[] buffer) =>
-        stream.Write(buffer, 0, buffer.Length);
-}
-#endif

CliFx/Utils/Polyfills.Strings.cs

@@ -1,12 +0,0 @@
-// ReSharper disable CheckNamespace
-
-#if NETSTANDARD2_0
-internal static class StringPolyfills
-{
-    public static bool StartsWith(this string str, char c) =>
-        str.Length > 0 && str[0] == c;
-
-    public static bool EndsWith(this string str, char c) =>
-        str.Length > 0 && str[str.Length - 1] == c;
-}
-#endif

CliFx/Utils/StackFrame.cs

@@ -52,33 +52,35 @@ internal partial class StackFrame
     private const string NotSpace = @"[^\x20\t]";
 
     // Taken from https://github.com/atifaziz/StackTraceParser
-    private static readonly Regex Pattern = new(@"
+    private static readonly Regex Pattern = new(
+        $$"""
         ^
-            " + Space + @"*
-            \w+ " + Space + @"+
+        {{Space}}*
+        \w+ {{Space}}+
         (?<frame>
-                (?<type> " + NotSpace + @"+ ) \.
-                (?<method> " + NotSpace + @"+? ) " + Space + @"*
-                (?<params>  \( ( " + Space + @"* \)
-                               |                    (?<pt> .+?) " + Space + @"+ (?<pn> .+?)
-                                 (, " + Space + @"* (?<pt> .+?) " + Space + @"+ (?<pn> .+?) )* \) ) )
-                ( " + Space + @"+
+            (?<type> {{NotSpace}}+ ) \.
+            (?<method> {{NotSpace}}+? ) {{Space}}*
+            (?<params>  \( ( {{Space}}* \)
+                           |                    (?<pt> .+?) {{Space}}+ (?<pn> .+?)
+                             (, {{Space}}* (?<pt> .+?) {{Space}}+ (?<pn> .+?) )* \) ) )
+            ( {{Space}}+
                 ( # Microsoft .NET stack traces
-                    \w+ " + Space + @"+
+                \w+ {{Space}}+
                 (?<file> ( [a-z] \: # Windows rooted path starting with a drive letter
-                             | / )      # *nix rooted path starting with a forward-slash
+                         | / )      # Unix rooted path starting with a forward-slash
                          .+? )
-                    \: \w+ " + Space + @"+
+                \: \w+ {{Space}}+
                 (?<line> [0-9]+ ) \p{P}?
                 | # Mono stack traces
-                    \[0x[0-9a-f]+\] " + Space + @"+ \w+ " + Space + @"+
+                \[0x[0-9a-f]+\] {{Space}}+ \w+ {{Space}}+
                 <(?<file> [^>]+ )>
                 :(?<line> [0-9]+ )
                 )
             )?
         )
         \s*
-            $",
+        $
+        """,
         RegexOptions.IgnoreCase |
         RegexOptions.Multiline |
         RegexOptions.ExplicitCapture |
@@ -89,16 +91,17 @@ internal partial class StackFrame
 
     public static IEnumerable<StackFrame> ParseMany(string stackTrace)
     {
-        var matches = Pattern.Matches(stackTrace).Cast<Match>().ToArray();
+        var matches = Pattern.Matches(stackTrace).ToArray();
 
         if (matches.Length <= 0 || matches.Any(m => !m.Success))
         {
             // If parsing fails, we include the original stacktrace in the
             // exception so that it's shown to the user.
             throw new FormatException(
-                "Could not parse stacktrace:" +
-                Environment.NewLine +
-                stackTrace
+                $"""
+                Could not parse stacktrace:
+                {stackTrace}
+                """
             );
         }
 

Directory.Build.props

@@ -1,12 +1,13 @@
 <Project>
 
   <PropertyGroup>
-    <Version>2.2.4</Version>
+    <Version>2.3.2</Version>
     <Company>Tyrrrz</Company>
     <Copyright>Copyright (C) Oleksii Holub</Copyright>
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <WarningsAsErrors>nullable</WarningsAsErrors>
+    <CheckEolTargetFramework>false</CheckEolTargetFramework>
     <IsPackable>false</IsPackable>
   </PropertyGroup>
 

License.txt

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019-2022 Oleksii Holub
+Copyright (c) 2019-2023 Oleksii Holub
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Readme.md

@@ -1,7 +1,7 @@
 # CliFx
 
-[![Made in Ukraine](https://img.shields.io/badge/made_in-ukraine-ffd700.svg?labelColor=0057b7)](https://vshymanskyy.github.io/StandWithUkraine)
-[![Build](https://img.shields.io/github/workflow/status/Tyrrrz/CliFx/CI/master)](https://github.com/Tyrrrz/CliFx/actions)
+[![Made in Ukraine](https://img.shields.io/badge/made_in-ukraine-ffd700.svg?labelColor=0057b7)](https://tyrrrz.me/ukraine)
+[![Build](https://img.shields.io/github/actions/workflow/status/Tyrrrz/CliFx/main.yml?branch=master)](https://github.com/Tyrrrz/CliFx/actions)
 [![Coverage](https://img.shields.io/codecov/c/github/Tyrrrz/CliFx/master)](https://codecov.io/gh/Tyrrrz/CliFx)
 [![Version](https://img.shields.io/nuget/v/CliFx.svg)](https://nuget.org/packages/CliFx)
 [![Downloads](https://img.shields.io/nuget/dt/CliFx.svg)](https://nuget.org/packages/CliFx)
@@ -9,12 +9,12 @@
 [![Donate](https://img.shields.io/badge/donate-$$$-8a2be2.svg)](https://tyrrrz.me/donate)
 [![Fuck Russia](https://img.shields.io/badge/fuck-russia-e4181c.svg?labelColor=000000)](https://twitter.com/tyrrrz/status/1495972128977571848)
 
-> 🟢 **Project status**: active<sup>[[?]](https://github.com/Tyrrrz/.github/blob/master/docs/project-status.md)</sup>
+> 🟡 **Project status**: maintenance mode<sup>[[?]](https://github.com/Tyrrrz/.github/blob/master/docs/project-status.md)</sup>
 
-**CliFx** is a simple to use, yet powerful framework for building command line applications.
+**CliFx** is a simple to use, yet powerful framework for building command-line applications.
 Its primary goal is to completely take over the user input layer, allowing you to forget about infrastructural concerns and instead focus on writing your application.
 
-## Terms of use
+## Terms of use<sup>[[?]](https://github.com/Tyrrrz/.github/blob/master/docs/why-so-political.md)</sup>
 
 By using this project or its source code, for any purpose and in any shape or form, you grant your **implicit agreement** to all the following statements:
 
@@ -23,7 +23,7 @@ By using this project or its source code, for any purpose and in any shape or fo
 - You **support Ukraine's territorial integrity, including its claims over temporarily occupied territories of Crimea and Donbas**
 - You **reject false narratives perpetuated by Russian state propaganda**
 
-To learn more about the war and how you can help, [click here](https://tyrrrz.me). Glory to Ukraine! 🇺🇦
+To learn more about the war and how you can help, [click here](https://tyrrrz.me/ukraine). Glory to Ukraine! 🇺🇦
 
 ## Install
 
@@ -34,7 +34,7 @@ To learn more about the war and how you can help, [click here](https://tyrrrz.me
 - Complete application framework, not just an argument parser
 - Minimum boilerplate and easy to get started
 - Class-first configuration via attributes
-- Comprehensive autogenerated help text
+- Comprehensive auto-generated help text
 - Support for deeply nested command hierarchies
 - Graceful cancellation via interrupt signals
 - Support for reading and writing binary data
@@ -49,14 +49,14 @@ To learn more about the war and how you can help, [click here](https://tyrrrz.me
 
 ## Usage
 
-### Quick start
+### Quick overview
 
-![quick start animated](https://i.imgur.com/uouNh2u.gif)
-
-To turn your program into a command line interface, modify your `Main` method so that it delegates execution to `CliApplication`.
-You can use `CliApplicationBuilder` to fluently create and configure an instance of `CliApplication`:
+To turn your program into a command-line interface, modify the `Main()` method so that it delegates the execution to an instance of `CliApplication`.
+You can use `CliApplicationBuilder` to simplify the process of creating and configuring an application:
 
 ```csharp
+using CliFx;
+
 public static class Program
 {
     public static async Task<int> Main() =>
@@ -67,81 +67,29 @@ public static class Program
 }
 ```
 
-> ⚠️ Ensure that your `Main()` method returns the integer exit code provided by `CliApplication.RunAsync()`, as shown in the above example.
-Exit code is used to communicate execution result to the parent process, so it's important that your program returns it.
+> **Warning**:
+> Ensure that your `Main()` method returns the integer exit code provided by `CliApplication.RunAsync()`, as shown in the above example.
+> Exit code is used to communicate execution result to the parent process, so it's important that your program propagates it.
 
-The code above calls `AddCommandsFromThisAssembly()` to scan and resolve command types defined within the current assembly.
-Commands are entry points, through which the user can interact with your application.
+> **Note**:
+> When calling `CliApplication.RunAsync()`, **CliFx** resolves command-line arguments and environment variables from `Environment.GetCommandLineArgs()` and `Environment.GetEnvironmentVariables()` respectively.
+> You can also provide them manually using one of the alternative overloads.
 
-To define a command, create a new class by implementing the `ICommand` interface and annotate it with the `[Command]` attribute:
+The code above uses `AddCommandsFromThisAssembly()` to detect command types defined within the current project and register them on the application.
+Commands are independent entry points, through which the user can interact with your program.
+
+To define a command, create a class that implements the `ICommand` interface and annotate it with the `[Command]` attribute:
 
 ```csharp
-[Command]
-public class HelloWorldCommand : ICommand
-{
-    public ValueTask ExecuteAsync(IConsole console)
-    {
-        console.Output.WriteLine("Hello world!");
+using CliFx;
+using CliFx.Attributes;
 
-        // Return default task if the command is not asynchronous
-        return default;
-    }
-}
-```
-
-In order to implement `ICommand`, the class needs to define an `ExecuteAsync(...)` method.
-This is the method that gets called by the framework when the user decides to execute this command.
-
-As a parameter, this method takes an instance of `IConsole`, which is an abstraction around the system console.
-Use this abstraction in place of `System.Console` whenever you need to write output, read input, or otherwise interact with the console.
-
-With the basic setup above, the user can now run the application and get a greeting in return:
-
-```sh
-> dotnet myapp.dll
-
-Hello world!
-```
-
-Out of the box, the application also comes with built-in `--help` and `--version` options.
-They can be used to show help text or application version respectively:
-
-```sh
-> dotnet myapp.dll --help
-
-MyApp v1.0
-
-USAGE
-  dotnet myapp.dll [options]
-
-OPTIONS
-  -h|--help         Shows help text.
-  --version         Shows version information.
-```
-
-```sh
-> dotnet myapp.dll --version
-
-v1.0
-```
-
-### Parameters and options
-
-Commands can be configured to take input from command line arguments.
-To do that, you need to add properties to the command class and annotate them with special attributes.
-
-In **CliFx**, there are two types of argument bindings: **parameters** and **options**.
-Parameters are positional arguments identified by the order they appear in, while options represent sets of arguments identified by their name.
-
-As an example, here's a command that calculates the logarithm of a value, using a parameter binding to specify the input and an option binding to configure the logarithm base:
-
-```csharp
-[Command]
+[Command(Description = "Calculates the logarithm of a value.")]
 public class LogCommand : ICommand
 {
     // Order: 0
     [CommandParameter(0, Description = "Value whose logarithm is to be found.")]
-    public double Value { get; init; }
+    public required double Value { get; init; }
 
     // Name: --base
     // Short name: -b
@@ -153,46 +101,61 @@ public class LogCommand : ICommand
         var result = Math.Log(Value, Base);
         console.Output.WriteLine(result);
 
+        // If the execution is not meant to be asynchronous,
+        // return an empty task at the end of the method.
         return default;
     }
 }
 ```
 
-In order to execute this command, at a minimum, the user needs to provide the input value:
+In order to implement `ICommand`, the class needs to define an `ExecuteAsync(...)` method.
+This is the method that gets called by the framework when the user decides to execute the command.
+
+As the only parameter, this method takes an instance of `IConsole`, which is an abstraction around the system console.
+Use this abstraction in place of `System.Console` whenever you need to write output, read input, or otherwise interact with the console.
+
+In most cases, you will also want to define input bindings, which are properties annotated by the `[CommandParameter]` and `[CommandOption]` attributes.
+These bindings provide a way to map command-line arguments into structured data that can be used by the command.
+
+The command in the above example serves as a simple logarithm calculator and defines two inputs: a positional parameter for the input value and a named option for the logarithm base.
+In order to execute this command, at minimum, the user needs to provide the input value:
 
 ```sh
-> dotnet myapp.dll 10000
+$ dotnet myapp.dll 10000
 
 4
 ```
 
-They can also pass the `base` option to override the default logarithm base of 10:
+They can also pass the `-b|--base` option to override the default logarithm base of `10`:
 
 ```sh
-> dotnet myapp.dll 729 -b 3
+$ dotnet myapp.dll 729 -b 3
 
 6
 ```
 
-In case the user forgets to specify the `value` parameter, the application will exit with an error:
+In case the user forgets to specify the required `value` parameter, the application will instead exit with an error:
 
 ```sh
-> dotnet myapp.dll -b 10
+$ dotnet myapp.dll -b 10
 
 Missing required parameter(s):
 <value>
 ```
 
-Available parameters and options are also listed in the command's help text, which can be accessed by passing the `--help` option:
+Out of the box, **CliFx** also provides a built-in `--help` option, which generates a help screen that lists all parameters and options available for the command:
 
 ```sh
-> dotnet myapp.dll --help
+$ dotnet myapp.dll --help
 
 MyApp v1.0
 
 USAGE
   dotnet myapp.dll <value> [options]
 
+DESCRIPTION
+  Calculates the logarithm of a value.  
+
 PARAMETERS
 * value             Value whose logarithm is to be found.
 
@@ -202,21 +165,9 @@ OPTIONS
   --version         Shows version information.
 ```
 
-Overall, parameters and options are both used to consume input from the command line, but they differ in a few important ways:
-
-|                    | Parameters                                                                                            | Options                                                                                         |
-|--------------------|-------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
-| **Identification** | Positional (by relative order).                                                                       | Named (by name or short name).                                                                  |
-| **Requiredness**   | Required by default. Only the last parameter can be configured to be optional.                        | Optional by default. Any option can be configured to be required without limitations.           |
-| **Arity**          | Depends on the property type. Only the last parameter can be bound to a non-scalar type (i.e. array). | Depends on the property type. Any option can be bound to a non-scalar type without limitations. |
-| **Fallback**       | —                                                                                                     | Can be configured to use an environment variable as fallback, in case the option isn't set.     |
-
-As a general guideline, it's recommended to use parameters for required inputs that the command can't function without.
-Use options for all other non-required inputs or when specifying the name explicitly makes the usage clearer.
-
 ### Argument syntax
 
-This library employs the POSIX argument syntax, which is used in most modern command line tools.
+This library employs a variation of the POSIX argument syntax, which is used in most modern command-line tools.
 Here are some examples of how it works:
 
 - `myapp --foo bar` sets option `"foo"` to value `"bar"`
@@ -227,26 +178,83 @@ Here are some examples of how it works:
 - `myapp -xqf bar` sets options `'x'` and `'q'` without value, and option `'f'` to value `"bar"`
 - `myapp -i file1.txt file2.txt` sets option `'i'` to a sequence of values `"file1.txt"` and `"file2.txt"`
 - `myapp -i file1.txt -i file2.txt` sets option `'i'` to a sequence of values `"file1.txt"` and `"file2.txt"`
-- `myapp cmd abc -o` routes to command `cmd` (assuming it's an existing command) with parameter `abc` and sets option `'o'` without value
+- `myapp cmd abc -o` routes to command `cmd` (assuming it's a command) with parameter `abc` and sets option `'o'` without value
 
 Additionally, argument parsing in **CliFx** aims to be as deterministic as possible, ideally yielding the same result regardless of the application configuration.
-In fact, the only context-sensitive part in the parser is the command name resolution, which needs to know the list of available commands in order to discern between arguments that correspond to command name and arguments which map as parameters.
+In fact, the only context-sensitive part in the parser is the command name resolution, which needs to know the list of available commands in order to discern them from parameters.
 
 The parser's context-free nature has several implications on how it consumes arguments.
-For example, passing `myapp -i file1.txt file2.txt` will always be parsed as an option with multiple values, regardless of the arity of the underlying property it's bound to.
+For example, `myapp -i file1.txt file2.txt` will always be parsed as an option with multiple values, regardless of the arity of the underlying property it's bound to.
 Similarly, unseparated arguments in the form of `myapp -ofile` will be treated as five distinct options `'o'`, `'f'`, `'i'`, `'l'`, `'e'`, instead of `'o'` being set to value `"file"`.
 
-Because of these rules, order of arguments is semantically important and must always follow this pattern:
+These rules also make the order of arguments important — command-line string is expected to follow this pattern:
 
-```txt
-[directives] [command name] [parameters] [options]
+```sh
+$ myapp [...directives] [command] [...parameters] [...options]
 ```
 
+### Parameters and options
+
+**CliFx** supports two types of argument bindings: **parameters** and **options**.
+Parameters are bound from arguments based on the order they appear in, while options are bound by their name.
+
+Besides that, they also differ in the following ways:
+
+- Parameters are required by default, while options are not.
+
+  - You can make an option required by setting `IsRequired = true` on the corresponding attribute or by adding the `required` keyword to the property declaration (introduced in C# 11):
+
+      ```csharp
+      // Any option can be required or optional without restrictions
+      [CommandOption("foo")]
+      public required string RequiredOption { get; init; }
+      ```
+
+  - To make a parameter optional, you can set `IsRequired = false`, but only the last parameter (by order) can be configured in such way:
+
+    ```csharp
+    // Only the last parameter can be optional
+    [CommandParameter(0, IsRequired = false)]
+    public string? OptionalParameter { get; init; }
+    ```
+
+- Parameters are primarily used for scalar (non-enumerable) properties, while options can be used for both scalar and non-scalar properties.
+
+  - You can bind an option to a property of a non-scalar type, such as `IReadOnlyList<T>`:
+
+    ```csharp
+    // Any option can be non-scalar
+    [CommandOption("foo")]
+    public required IReadOnlyList<string> NonScalarOption { get; init; }
+    ```
+
+  - You can bind a parameter to a non-scalar property, but only if it's the last parameter in the command:
+  
+    ```csharp
+    // Only the last parameter can be non-scalar
+    [CommandParameter(0)]
+    public required IReadOnlyList<string> NonScalarParameter { get; init; }
+    ```
+
+- Options can rely on an environment variable for fallback, while parameters cannot:
+
+  ```csharp
+  // If the value is not provided directly, it will be read
+  // from the environment variable instead.
+  // This works for both scalar and non-scalar properties.
+  [CommandOption("foo", EnvironmentVariable = "ENV_FOO")]
+  public required string OptionWithFallback { get; init; }
+  ```
+
+> **Note**:
+> **CliFx** has a set of built-in analyzers that detect common errors in command definitions.
+> Your code will not compile if a command contains duplicate options, overlapping parameters, or otherwise invalid configuration.
+
 ### Value conversion
 
-Parameters and options can have the following underlying types:
+Parameters and options can be bound to properties with the following underlying types:
 
-- Standard types
+- Basic types
   - Primitive types (`int`, `bool`, `double`, `ulong`, `char`, etc.)
   - Date and time types (`DateTime`, `DateTimeOffset`, `TimeSpan`)
   - Enum types (converted from either name or numeric value)
@@ -271,7 +279,7 @@ public class FileSizeCalculatorCommand : ICommand
     // FileInfo is string-initializable and IReadOnlyList<T> can be assigned from an array,
     // so the value of this property can be mapped from a sequence of arguments.
     [CommandParameter(0)]
-    public IReadOnlyList<FileInfo> Files { get; init; }
+    public required IReadOnlyList<FileInfo> Files { get; init; }
 
     public ValueTask ExecuteAsync(IConsole console)
     {
@@ -285,33 +293,7 @@ public class FileSizeCalculatorCommand : ICommand
 ```
 
 ```sh
-> dotnet myapp.dll file1.bin file2.exe
-
-Total file size: 186368 bytes
-```
-
-Same command, but using an option for the list of files instead:
-
-```csharp
-[Command]
-public class FileSizeCalculatorCommand : ICommand
-{
-    [CommandOption("files")]
-    public IReadOnlyList<FileInfo> Files { get; init; }
-
-    public ValueTask ExecuteAsync(IConsole console)
-    {
-        var totalSize = Files.Sum(f => f.Length);
-
-        console.Output.WriteLine($"Total file size: {totalSize} bytes");
-
-        return default;
-    }
-}
-```
-
-```sh
-> dotnet myapp.dll --files file1.bin file2.exe
+$ dotnet myapp.dll file1.bin file2.exe
 
 Total file size: 186368 bytes
 ```
@@ -342,13 +324,13 @@ public class SurfaceCalculatorCommand : ICommand
 {
     // Custom converter is used to map raw argument values
     [CommandParameter(0, Converter = typeof(VectorConverter))]
-    public Vector2 PointA { get; init; }
+    public required Vector2 PointA { get; init; }
 
     [CommandParameter(1, Converter = typeof(VectorConverter))]
-    public Vector2 PointB { get; init; }
+    public required Vector2 PointB { get; init; }
 
     [CommandParameter(2, Converter = typeof(VectorConverter))]
-    public Vector2 PointC { get; init; }
+    public required Vector2 PointC { get; init; }
 
     public ValueTask ExecuteAsync(IConsole console)
     {
@@ -366,10 +348,16 @@ public class SurfaceCalculatorCommand : ICommand
 }
 ```
 
+```sh
+$ dotnet myapp.dll 0x0 0x10 10x0
+
+Triangle surface area: 50
+```
+
 ### Multiple commands
 
-In order to facilitate a variety of different workflows, command line applications may provide the user with more than just a single command.
-Complex applications may also nest commands within each other, employing a multi-level hierarchical structure.
+In order to facilitate a variety of different workflows, command-line applications may provide the user with more than just a single command.
+Complex applications may also nest commands underneath each other, employing a multi-level hierarchical structure.
 
 With **CliFx**, this is achieved by simply giving each command a unique name through the `[Command]` attribute.
 Commands that have common name segments are considered to be hierarchically related, which affects how they're listed in the help text.
@@ -404,13 +392,13 @@ public class SubCommand : ICommand
 }
 ```
 
-Once configured, the user can execute a specific command by including its name in the passed arguments.
+Once configured, the user can execute a specific command by pre-pending its name to the passed arguments.
 For example, running `dotnet myapp.dll cmd1 arg1 -p 42` will execute `FirstCommand` in the above example.
 
 Requesting help will show direct subcommands of the current command:
 
 ```sh
-> dotnet myapp.dll --help
+$ dotnet myapp.dll --help
 
 MyApp v1.0
 
@@ -432,7 +420,7 @@ You can run `dotnet myapp.dll [command] --help` to show help on a specific comma
 The user can also refine their help request by querying it on a specific command:
 
 ```sh
-> dotnet myapp.dll cmd1 --help
+$ dotnet myapp.dll cmd1 --help
 
 USAGE
   dotnet myapp.dll cmd1 [options]
@@ -447,8 +435,9 @@ COMMANDS
 You can run `dotnet myapp.dll cmd1 [command] --help` to show help on a specific command.
 ```
 
-> 💡 Defining a default (unnamed) command is not required.
-If it's absent, running the application without specifying a command will just show the root level help text.
+> **Note**:
+> Defining a default (unnamed) command is not required.
+> If it's absent, running the application without specifying a command will just show the root-level help text.
 
 ### Reporting errors
 
@@ -459,11 +448,11 @@ This special exception can be used to print an error message to the console, ret
 [Command]
 public class DivideCommand : ICommand
 {
-    [CommandOption("dividend", IsRequired = true)]
-    public double Dividend { get; init; }
+    [CommandOption("dividend")]
+    public required double Dividend { get; init; }
 
-    [CommandOption("divisor", IsRequired = true)]
-    public double Divisor { get; init; }
+    [CommandOption("divisor")]
+    public required double Divisor { get; init; }
 
     public ValueTask ExecuteAsync(IConsole console)
     {
@@ -482,25 +471,25 @@ public class DivideCommand : ICommand
 ```
 
 ```sh
-> dotnet myapp.dll --dividend 10 --divisor 0
+$ dotnet myapp.dll --dividend 10 --divisor 0
 
 Division by zero is not supported.
 
-
-> $LastExitCode
+$ echo $?
 
 133
 ```
 
-> ⚠️ Even though exit codes are represented by 32-bit integers in .NET, using values outside of 8-bit unsigned range will cause an overflow on Unix systems.
-To avoid unexpected results, use numbers between 1 and 255 for exit codes that indicate failure.
+> **Warning**:
+> Even though exit codes are represented by 32-bit integers in .NET, using values outside 8-bit unsigned range will cause an overflow on Unix systems.
+> To avoid unexpected results, use numbers between 1 and 255 for exit codes that indicate failure.
 
 ### Graceful cancellation
 
 Console applications support the concept of interrupt signals, which can be issued by the user to abort the currently ongoing operation.
 If your command performs critical work, you can intercept these signals to handle cancellation requests in a graceful way.
 
-To make a command cancellation-aware, call `console.RegisterCancellationHandler()` to register the signal handler and obtain the corresponding `CancellationToken`.
+In order to make the command cancellation-aware, call `console.RegisterCancellationHandler()` to register the signal handler and obtain the corresponding `CancellationToken`.
 Once this method is called, the program will no longer terminate on an interrupt signal but will instead trigger the token, so it's important to be able to process it correctly.
 
 ```csharp
@@ -525,15 +514,16 @@ public class CancellableCommand : ICommand
 }
 ```
 
-> ⚠️ Forceful termination of a command can only be delayed once.
-If the user issues a second interrupt signal, the process will be killed immediately without waiting for graceful cancellation.
+> **Warning**:
+> Cancellation handler is only respected when the user sends the interrupt signal for the first time.
+> If the user decides to issue the signal again, the application will terminate immediately regardless of whether the command is cancellation-aware.
 
 ### Type activation
 
-Because **CliFx** takes responsibility for the application's entire lifecycle, it needs to be capable of instantiating various user-defined types at runtime.
+Because **CliFx** takes responsibility for the application's entire lifecycle, it needs to be capable of instantiating various user-defined types at run-time.
 To facilitate that, it uses an interface called `ITypeActivator` that determines how to create a new instance of a given type.
 
-The default implementation of `ITypeActivator` only supports types that have public parameterless constructors, which is sufficient for majority of scenarios.
+The default implementation of `ITypeActivator` only supports types that have public parameterless constructors, which is sufficient for the majority of scenarios.
 However, in some cases you may also want to define a custom initializer, for example when integrating with an external dependency container.
 
 The following example shows how to configure your application to use [`Microsoft.Extensions.DependencyInjection`](https://nuget.org/packages/Microsoft.Extensions.DependencyInjection) as the type activator in **CliFx**:
@@ -555,7 +545,7 @@ public static class Program
 
         return await new CliApplicationBuilder()
             .AddCommandsFromThisAssembly()
-            .UseTypeActivator(serviceProvider.GetService)
+            .UseTypeActivator(serviceProvider)
             .Build()
             .RunAsync();
     }
@@ -653,18 +643,18 @@ In order to run the application in debug mode, use the `[debug]` directive.
 This will cause the program to launch in a suspended state, waiting for debugger to be attached to the process:
 
 ```sh
-> dotnet myapp.dll [debug] cmd -o
+$ dotnet myapp.dll [debug] cmd -o
 
 Attach debugger to PID 3148 to continue.
 ```
 
 To run the application in preview mode, use the `[preview]` directive.
-This will short-circuit the execution and instead print the consumed command line arguments as they were parsed, along with resolved environment variables:
+This will short-circuit the execution and instead print the consumed command-line arguments as they were parsed, along with resolved environment variables:
 
 ```sh
-> dotnet myapp.dll [preview] cmd arg1 arg2 -o foo --option bar1 bar2
+$ dotnet myapp.dll [preview] cmd arg1 arg2 -o foo --option bar1 bar2
 
-Command line:
+Command-line:
   cmd <arg1> <arg2> [-o foo] [--option bar1 bar2]
 
 Environment:
@@ -682,38 +672,7 @@ var app = new CliApplicationBuilder()
     .Build();
 ```
 
-### Environment variables
-
-An option can be configured to use a specific environment variable as fallback.
-If the user does not provide value for such option through command line arguments, the current value of the environment variable will be used instead.
-
-```csharp
-[Command]
-public class AuthCommand : ICommand
-{
-    [CommandOption("token", IsRequired = true, EnvironmentVariable = "AUTH_TOKEN")]
-    public string AuthToken { get; init; }
-
-    public ValueTask ExecuteAsync(IConsole console)
-    {
-        console.Output.WriteLine(AuthToken);
-
-        return default;
-    }
-}
-```
-
-```sh
-> $env:AUTH_TOKEN="test"
-
-> dotnet myapp.dll
-
-test
-```
-
-Environment variables can be configured for options of non-scalar types (arrays, lists, etc.) as well.
-In such case, the values of the environment variable will be split by `Path.PathSeparator` (`;` on Windows, `:` on Linux).
-
 ## Etymology
 
-**CliFx** is made out of "Cli" for "Command Line Interface" and "Fx" for "Framework". It's pronounced as "cliff ex".
+**CliFx** is made out of "Cli" for "Command-line Interface" and "Fx" for "Framework".
+It's pronounced as "cliff ex".