From 77c7faa759b721fd44c4a63cb84ebacb548a65cd Mon Sep 17 00:00:00 2001
From: Alexey Golub <Tyrrrrrr@gmail.com>
Date: Wed, 17 Jul 2019 23:06:16 +0300
Subject: [PATCH] Introduce ICommand

---
 CliFx/Command.cs                   |  2 +-
 CliFx/ICommand.cs                  | 10 ++++++++++
 CliFx/Internal/CommandType.cs      |  4 +---
 CliFx/Services/CommandResolver.cs  |  2 +-
 CliFx/Services/ICommandResolver.cs |  2 +-
 5 files changed, 14 insertions(+), 6 deletions(-)
 create mode 100644 CliFx/ICommand.cs

diff --git a/CliFx/Command.cs b/CliFx/Command.cs
index 7442e7f..f8797c3 100644
--- a/CliFx/Command.cs
+++ b/CliFx/Command.cs
@@ -4,7 +4,7 @@ using CliFx.Models;
 
 namespace CliFx
 {
-    public abstract class Command
+    public abstract class Command : ICommand
     {
         public virtual ExitCode Execute() => throw new InvalidOperationException(
             "Can't execute command because its execution method is not defined. " +
diff --git a/CliFx/ICommand.cs b/CliFx/ICommand.cs
new file mode 100644
index 0000000..8cbaccd
--- /dev/null
+++ b/CliFx/ICommand.cs
@@ -0,0 +1,10 @@
+using System.Threading.Tasks;
+using CliFx.Models;
+
+namespace CliFx
+{
+    public interface ICommand
+    {
+        Task<ExitCode> ExecuteAsync();
+    }
+}
\ No newline at end of file
diff --git a/CliFx/Internal/CommandType.cs b/CliFx/Internal/CommandType.cs
index 602b1af..609d710 100644
--- a/CliFx/Internal/CommandType.cs
+++ b/CliFx/Internal/CommandType.cs
@@ -33,9 +33,7 @@ namespace CliFx.Internal
     internal partial class CommandType
     {
         public static bool IsValid(Type type) =>
-            // Derives from Command
-            type.IsDerivedFrom(typeof(Command)) &&
-            // Marked with DefaultCommandAttribute or CommandAttribute
+            type.GetInterfaces().Contains(typeof(ICommand)) &&
             type.IsDefined(typeof(CommandAttribute));
 
         public static CommandType Initialize(Type type)
diff --git a/CliFx/Services/CommandResolver.cs b/CliFx/Services/CommandResolver.cs
index 2ec7693..029265d 100644
--- a/CliFx/Services/CommandResolver.cs
+++ b/CliFx/Services/CommandResolver.cs
@@ -74,7 +74,7 @@ namespace CliFx.Services
                 $"Apply {nameof(CommandAttribute)} to give command a name.");
         }
 
-        public Command ResolveCommand(CommandOptionSet optionSet)
+        public ICommand ResolveCommand(CommandOptionSet optionSet)
         {
             // Get command type
             var commandType = !optionSet.CommandName.IsNullOrWhiteSpace()
diff --git a/CliFx/Services/ICommandResolver.cs b/CliFx/Services/ICommandResolver.cs
index 1b3b4d0..983b848 100644
--- a/CliFx/Services/ICommandResolver.cs
+++ b/CliFx/Services/ICommandResolver.cs
@@ -4,6 +4,6 @@ namespace CliFx.Services
 {
     public interface ICommandResolver
     {
-        Command ResolveCommand(CommandOptionSet optionSet);
+        ICommand ResolveCommand(CommandOptionSet optionSet);
     }
 }
\ No newline at end of file