Adding in cancellation support for InvokeAsync

src/System.CommandLine.ApiCompatibility.Tests/ApiCompatibilityApprovalTests.System_CommandLine_api_is_not_changed.approved.txt

@@ -66,8 +66,8 @@ System.CommandLine
   public static class CommandExtensions
     public static System.Int32 Invoke(this Command command, System.String[] args, IConsole console = null)
     public static System.Int32 Invoke(this Command command, System.String commandLine, IConsole console = null)
-    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Command command, System.String[] args, IConsole console = null)
-    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Command command, System.String commandLine, IConsole console = null)
+    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Command command, System.String[] args, IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
+    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Command command, System.String commandLine, IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
     public static ParseResult Parse(this Command command, System.String[] args)
     public static ParseResult Parse(this Command command, System.String commandLine)
   public class CommandLineBuilder
@@ -357,8 +357,8 @@ System.CommandLine.Help
 System.CommandLine.Invocation
   public interface IInvocationResult
     public System.Void Apply(InvocationContext context)
-  public class InvocationContext
-    .ctor(System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null)
+  public class InvocationContext, System.IDisposable
+    .ctor(System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
     public System.CommandLine.Binding.BindingContext BindingContext { get; }
     public System.CommandLine.IConsole Console { get; set; }
     public System.Int32 ExitCode { get; set; }
@@ -368,6 +368,7 @@ System.CommandLine.Invocation
     public System.CommandLine.Parsing.Parser Parser { get; }
     public System.CommandLine.ParseResult ParseResult { get; set; }
     public System.Threading.CancellationToken GetCancellationToken()
+    public System.Void LinkToken(System.Threading.CancellationToken token)
   public delegate InvocationMiddleware : System.MulticastDelegate, System.ICloneable, System.Runtime.Serialization.ISerializable
     .ctor(System.Object object, System.IntPtr method)
     public System.IAsyncResult BeginInvoke(InvocationContext context, System.Func<InvocationContext,System.Threading.Tasks.Task> next, System.AsyncCallback callback, System.Object object)
@@ -450,12 +451,12 @@ System.CommandLine.Parsing
     public static System.String Diagram(this System.CommandLine.ParseResult parseResult)
     public static System.Boolean HasOption(this System.CommandLine.ParseResult parseResult, System.CommandLine.Option option)
     public static System.Int32 Invoke(this System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null)
-    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null)
+    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this System.CommandLine.ParseResult parseResult, System.CommandLine.IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
   public static class ParserExtensions
     public static System.Int32 Invoke(this Parser parser, System.String commandLine, System.CommandLine.IConsole console = null)
     public static System.Int32 Invoke(this Parser parser, System.String[] args, System.CommandLine.IConsole console = null)
-    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Parser parser, System.String commandLine, System.CommandLine.IConsole console = null)
-    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Parser parser, System.String[] args, System.CommandLine.IConsole console = null)
+    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Parser parser, System.String commandLine, System.CommandLine.IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
+    public static System.Threading.Tasks.Task<System.Int32> InvokeAsync(this Parser parser, System.String[] args, System.CommandLine.IConsole console = null, System.Threading.CancellationToken cancellationToken = null)
     public static System.CommandLine.ParseResult Parse(this Parser parser, System.String commandLine)
   public abstract class SymbolResult
     public System.Collections.Generic.IReadOnlyList<SymbolResult> Children { get; }

src/System.CommandLine.Tests/Invocation/CancelOnProcessTerminationTests.cs

@@ -1,12 +1,13 @@
 // Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using FluentAssertions;
+using System.CommandLine.Invocation;
 using System.CommandLine.Parsing;
 using System.CommandLine.Tests.Utility;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
-using FluentAssertions;
 using Xunit;
 using Process = System.Diagnostics.Process;
 

src/System.CommandLine.Tests/Invocation/InvocationContextTests.cs

@@ -0,0 +1,64 @@
+using FluentAssertions;
+using System.CommandLine;
+using System.CommandLine.Invocation;
+using System.CommandLine.Parsing;
+using System.Threading;
+using Xunit;
+
+namespace System.CommandLine.Tests.Invocation
+{
+    public class InvocationContextTests
+    {
+        [Fact]
+        public void InvocationContext_with_cancellation_token_returns_it()
+        {
+            using CancellationTokenSource cts = new();
+            var parseResult = new CommandLineBuilder(new RootCommand())
+                .Build()
+                .Parse("");
+            using InvocationContext context = new(parseResult, cancellationToken: cts.Token);
+
+            var token = context.GetCancellationToken();
+
+            token.IsCancellationRequested.Should().BeFalse();
+            cts.Cancel();
+            token.IsCancellationRequested.Should().BeTrue();
+        }
+
+        [Fact]
+        public void InvocationContext_with_linked_cancellation_token_can_cancel_by_passed_token()
+        {
+            using CancellationTokenSource cts1 = new();
+            using CancellationTokenSource cts2 = new();
+            var parseResult = new CommandLineBuilder(new RootCommand())
+                .Build()
+                .Parse("");
+            using InvocationContext context = new(parseResult, cancellationToken: cts1.Token);
+            context.LinkToken(cts2.Token);
+
+            var token = context.GetCancellationToken();
+
+            token.IsCancellationRequested.Should().BeFalse();
+            cts1.Cancel();
+            token.IsCancellationRequested.Should().BeTrue();
+        }
+
+        [Fact]
+        public void InvocationContext_with_linked_cancellation_token_can_cancel_by_linked_token()
+        {
+            using CancellationTokenSource cts1 = new();
+            using CancellationTokenSource cts2 = new();
+            var parseResult = new CommandLineBuilder(new RootCommand())
+                .Build()
+                .Parse("");
+            using InvocationContext context = new(parseResult, cancellationToken: cts1.Token);
+            context.LinkToken(cts2.Token);
+
+            var token = context.GetCancellationToken();
+
+            token.IsCancellationRequested.Should().BeFalse();
+            cts2.Cancel();
+            token.IsCancellationRequested.Should().BeTrue();
+        }
+    }
+}

src/System.CommandLine.Tests/Invocation/InvocationExtensionsTests.cs

@@ -1,7 +1,9 @@
 // Copyright (c) .NET Foundation and contributors. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.CommandLine.Invocation;
 using System.CommandLine.IO;
+using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
 using Xunit;
@@ -149,5 +151,28 @@ public void RootCommand_Invoke_can_set_custom_result_code()
 
             resultCode.Should().Be(123);
         }
+
+        [Fact]
+        public async Task Command_InvokeAsync_with_cancelation_token_invokes_command_handler()
+        {
+            CancellationTokenSource cts = new();
+            var command = new Command("test");
+            command.SetHandler((InvocationContext context) =>
+            {
+                CancellationToken cancellationToken = context.GetCancellationToken();
+                Assert.True(cancellationToken.CanBeCanceled);
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    return Task.FromResult(42);
+                }
+
+                return Task.FromResult(0);
+            });
+
+            cts.Cancel();
+            int rv = await command.InvokeAsync("test", cancellationToken: cts.Token);
+
+            rv.Should().Be(42);
+        }
     }
 }

src/System.CommandLine.Tests/Invocation/InvocationPipelineTests.cs

@@ -2,9 +2,11 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.CommandLine.Help;
+using System.CommandLine.Invocation;
 using System.CommandLine.IO;
 using System.CommandLine.Parsing;
 using System.Linq;
+using System.Threading;
 using System.Threading.Tasks;
 using FluentAssertions;
 using Xunit;
@@ -44,7 +46,7 @@ public async Task InvokeAsync_chooses_the_appropriate_command()
 
             var parser = new CommandLineBuilder(new RootCommand
                          {
-                             first, 
+                             first,
                              second
                          })
                          .Build();
@@ -327,5 +329,39 @@ public async Task When_help_builder_factory_is_specified_it_is_used_to_create_th
             handlerWasCalled.Should().BeTrue();
             factoryWasCalled.Should().BeTrue();
         }
+
+        [Fact]
+        public async Task Command_InvokeAsync_can_cancel_from_middleware()
+        {
+            var handlerWasCalled = false;
+            var isCancelRequested = false;
+
+            var command = new Command("the-command");
+            command.SetHandler((InvocationContext context) =>
+            {
+                handlerWasCalled = true;
+                isCancelRequested = context.GetCancellationToken().IsCancellationRequested;
+                return Task.FromResult(0);
+            });
+
+
+            using CancellationTokenSource cts = new();
+            var parser = new CommandLineBuilder(new RootCommand
+                         {
+                             command
+                         })
+                         .AddMiddleware(async (context, next) =>
+                         {
+                             context.LinkToken(cts.Token);
+                             cts.Cancel();
+                             await next(context);
+                         })
+                         .Build();
+
+            await parser.InvokeAsync("the-command");
+
+            handlerWasCalled.Should().BeTrue();
+            isCancelRequested.Should().BeTrue();
+        }
     }
 }

src/System.CommandLine.Tests/ParserTests.RootCommandAndArg0.cs

@@ -42,10 +42,11 @@ public void When_parsing_a_string_array_input_then_a_full_path_to_an_executable_
 
             command.Parse(Split("inner -x hello")).Errors.Should().BeEmpty();
 
-            command.Parse(Split($"{RootCommand.ExecutablePath} inner -x hello"))
-                   .Errors
-                   .Should()
-                   .ContainSingle(e => e.Message == $"{LocalizationResources.Instance.UnrecognizedCommandOrArgument(RootCommand.ExecutablePath)}");
+            var parserResult = command.Parse(Split($"\"{RootCommand.ExecutablePath}\" inner -x hello"));
+            parserResult
+               .Errors
+               .Should()
+               .ContainSingle(e => e.Message == LocalizationResources.Instance.UnrecognizedCommandOrArgument(RootCommand.ExecutablePath));
         }
 
         [Fact]
@@ -76,7 +77,7 @@ public void When_parsing_an_unsplit_string_then_input_a_full_path_to_an_executab
                 }
             };
 
-            var result2 = command.Parse($"{RootCommand.ExecutablePath} inner -x hello");
+            var result2 = command.Parse($"\"{RootCommand.ExecutablePath}\" inner -x hello");
 
             result2.RootCommandResult.Token.Value.Should().Be(RootCommand.ExecutablePath);
         }

src/System.CommandLine/Binding/BindingContext.cs

@@ -6,8 +6,6 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
-#nullable enable
-
 namespace System.CommandLine.Binding
 {
     /// <summary>