Add polyfill for TaskCompletionSource<T>.SetCanceled(...)

PolyShim.Tests/Net50/TaskCompletionSourceTests.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Xunit;
+
+namespace PolyShim.Tests.Net50;
+
+public class TaskCompletionSourceTests
+{
+    [Fact]
+    public async Task SetCanceled_Test()
+    {
+        // Arrange
+        var cancellationToken = new CancellationToken(true);
+        var tcs = new TaskCompletionSource<int>();
+
+        // Act
+        tcs.SetCanceled(cancellationToken);
+        var ex = await Assert.ThrowsAnyAsync<OperationCanceledException>(async () =>
+            await tcs.Task
+        );
+
+        // Assert
+        tcs.Task.IsCanceled.Should().BeTrue();
+        ex.CancellationToken.Should().Be(cancellationToken);
+        ex.CancellationToken.IsCancellationRequested.Should().BeTrue();
+    }
+
+    [Fact]
+    public void SetCanceled_AlreadyCompleted_Test()
+    {
+        // Arrange
+        var cancellationToken = new CancellationToken(true);
+        var tcs = new TaskCompletionSource<int>();
+        tcs.SetResult(42);
+
+        // Act & assert
+        Assert.ThrowsAny<InvalidOperationException>(() => tcs.SetCanceled(cancellationToken));
+    }
+}

PolyShim.Tests/NetCore10/TaskCompletionSourceTests.cs

@@ -16,14 +16,30 @@ public async Task TrySetCanceled_Test()
         var tcs = new TaskCompletionSource<int>();
 
         // Act
-        tcs.TrySetCanceled(cancellationToken);
+        var result = tcs.TrySetCanceled(cancellationToken);
         var ex = await Assert.ThrowsAnyAsync<OperationCanceledException>(async () =>
             await tcs.Task
         );
 
         // Assert
+        result.Should().BeTrue();
         tcs.Task.IsCanceled.Should().BeTrue();
         ex.CancellationToken.Should().Be(cancellationToken);
         ex.CancellationToken.IsCancellationRequested.Should().BeTrue();
     }
+
+    [Fact]
+    public void TrySetCanceled_AlreadyCompleted_Test()
+    {
+        // Arrange
+        var cancellationToken = new CancellationToken(true);
+        var tcs = new TaskCompletionSource<int>();
+        tcs.SetResult(42);
+
+        // Act
+        var result = tcs.TrySetCanceled(cancellationToken);
+
+        // Assert
+        result.Should().BeFalse();
+    }
 }

PolyShim/Net50/TaskCompletionSource.cs

@@ -0,0 +1,29 @@
+// The following comment is required to instruct analyzers to skip this file
+// <auto-generated/>
+
+#if FEATURE_TASK
+#if (NETCOREAPP && !NET5_0_OR_GREATER) || (NETFRAMEWORK) || (NETSTANDARD)
+#nullable enable
+// ReSharper disable RedundantUsingDirective
+// ReSharper disable CheckNamespace
+// ReSharper disable InconsistentNaming
+// ReSharper disable PartialTypeWithSinglePart
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+internal static partial class PolyfillExtensions
+{
+    extension<T>(TaskCompletionSource<T> source)
+    {
+        // https://learn.microsoft.com/dotnet/api/system.threading.tasks.taskcompletionsource-1.setcanceled#system-threading-tasks-taskcompletionsource-1-setcanceled(system-threading-cancellationtoken)
+        public void SetCanceled(CancellationToken cancellationToken)
+        {
+            if (!source.TrySetCanceled(cancellationToken))
+                throw new InvalidOperationException("The task is already completed, canceled, or failed.");
+        }
+    }
+}
+#endif
+#endif