Async command unit tests

src/Spectre.Console.Testing/Cli/CommandAppTester.cs

@@ -142,4 +142,50 @@ public sealed class CommandAppTester
 
         return new CommandAppResult(result, output, context, settings);
     }
+
+    /// <summary>
+    /// Runs the command application asynchronously.
+    /// </summary>
+    /// <param name="args">The arguments.</param>
+    /// <returns>The result.</returns>
+    public async Task<CommandAppResult> RunAsync(params string[] args)
+    {
+        var console = new TestConsole().Width(int.MaxValue);
+        return await RunAsync(args, console);
+    }
+
+    private async Task<CommandAppResult> RunAsync(string[] args, TestConsole console, Action<IConfigurator>? config = null)
+    {
+        CommandContext? context = null;
+        CommandSettings? settings = null;
+
+        var app = new CommandApp(Registrar);
+        _appConfiguration?.Invoke(app);
+
+        if (_configuration != null)
+        {
+            app.Configure(_configuration);
+        }
+
+        if (config != null)
+        {
+            app.Configure(config);
+        }
+
+        app.Configure(c => c.ConfigureConsole(console));
+        app.Configure(c => c.SetInterceptor(new CallbackCommandInterceptor((ctx, s) =>
+        {
+            context = ctx;
+            settings = s;
+        })));
+
+        var result = await app.RunAsync(args);
+
+        var output = console.Output
+            .NormalizeLineEndings()
+            .TrimLines()
+            .Trim();
+
+        return new CommandAppResult(result, output, context, settings);
+    }
 }

test/Spectre.Console.Cli.Tests/Data/Commands/AsynchronousCommand.cs

@@ -0,0 +1,28 @@
+namespace Spectre.Console.Tests.Data;
+
+public sealed class AsynchronousCommand : AsyncCommand<AsynchronousCommandSettings>
+{
+    private readonly IAnsiConsole _console;
+
+    public AsynchronousCommand(IAnsiConsole console)
+    {
+        _console = console;
+    }
+
+    public async override Task<int> ExecuteAsync(CommandContext context, AsynchronousCommandSettings settings)
+    {
+        // Simulate a long running asynchronous task
+        await Task.Delay(200);
+
+        if (settings.ThrowException)
+        {
+            throw new Exception($"Throwing exception asynchronously");
+        }
+        else
+        {
+            _console.WriteLine($"Finished executing asynchronously");
+        }
+
+        return 0;
+    }
+}

test/Spectre.Console.Cli.Tests/Data/Commands/ThrowingCommand.cs

@@ -7,7 +7,3 @@ public sealed class ThrowingCommand : Command<ThrowingCommandSettings>
         throw new InvalidOperationException("W00t?");
     }
 }
-
-public sealed class ThrowingCommandSettings : CommandSettings
-{
-}

test/Spectre.Console.Cli.Tests/Data/Settings/AsynchronousCommandSettings.cs

@@ -0,0 +1,8 @@
+namespace Spectre.Console.Tests.Data;
+
+public sealed class AsynchronousCommandSettings : CommandSettings
+{
+    [CommandOption("--ThrowException")]
+    [DefaultValue(false)]
+    public bool ThrowException { get; set; }
+}

test/Spectre.Console.Cli.Tests/Data/Settings/ThrowingCommandSettings.cs

@@ -0,0 +1,5 @@
+namespace Spectre.Console.Tests.Data;
+
+public sealed class ThrowingCommandSettings : CommandSettings
+{
+}

test/Spectre.Console.Cli.Tests/Unit/CommandAppTests.Async.cs

@@ -0,0 +1,70 @@
+namespace Spectre.Console.Tests.Unit.Cli;
+
+public sealed partial class CommandAppTests
+{
+    public sealed class Async
+    {
+        [Fact]
+        public async void Should_Execute_Command_Asynchronously()
+        {
+            // Given
+            var app = new CommandAppTester();
+            app.SetDefaultCommand<AsynchronousCommand>();
+            app.Configure(config =>
+            {
+                config.PropagateExceptions();
+            });
+
+            // When
+            var result = await app.RunAsync();
+
+            // Then
+            result.ExitCode.ShouldBe(0);
+            result.Output.ShouldBe("Finished executing asynchronously");
+        }
+
+        [Fact]
+        public async void Should_Handle_Exception_Asynchronously()
+        {
+            // Given
+            var app = new CommandAppTester();
+            app.SetDefaultCommand<AsynchronousCommand>();
+
+            // When
+            var result = await app.RunAsync(new[]
+                        {
+                        "--ThrowException",
+                        "true",
+                        });
+
+            // Then
+            result.ExitCode.ShouldBe(-1);
+        }
+
+        [Fact]
+        public async void Should_Throw_Exception_Asynchronously()
+        {
+            // Given
+            var app = new CommandAppTester();
+            app.SetDefaultCommand<AsynchronousCommand>();
+            app.Configure(config =>
+            {
+                config.PropagateExceptions();
+            });
+
+            // When
+            var result = await Record.ExceptionAsync(async () =>
+                    await app.RunAsync(new[]
+                        {
+                        "--ThrowException",
+                        "true",
+                        }));
+
+            // Then
+            result.ShouldBeOfType<Exception>().And(ex =>
+            {
+                ex.Message.ShouldBe("Throwing exception asynchronously");
+            });
+        }
+    }
+}