Add test for non-cancellable await

src/AsyncTools.Tests/WaitHandleExtensionsTests.cs

@@ -21,8 +21,31 @@ public void Should_CompleteTask_When_HandlerIsSet()
 
 		// Assert
 		Assert.DoesNotThrowAsync(() => task);
-		Assert.That(task.IsCompleted, Is.True);
-		Assert.That(task.IsCanceled, Is.False);
+		Assert.Multiple(() =>
+		{
+			Assert.That(task.IsCompleted, Is.True);
+			Assert.That(task.IsCanceled, Is.False);
+		});
+	}
+
+	[Test]
+	public void Should_CompleteTask_When_HandlerIsSetWithoutToken()
+	{
+		// Arrange
+		using var handler = new ManualResetEvent(initialState: false);
+
+		var task = handler.WaitAsync();
+
+		// Act
+		handler.Set();
+
+		// Assert
+		Assert.DoesNotThrowAsync(() => task);
+		Assert.Multiple(() =>
+		{
+			Assert.That(task.IsCompleted, Is.True);
+			Assert.That(task.IsCanceled, Is.False);
+		});
 	}
 
 	[Test]

src/AsyncTools/WaitHandleExtensions.cs

@@ -54,11 +54,14 @@ public static Task WaitAsync(
 			executeOnlyOnce: true
 		);
 
-		tcs.Task.ContinueWith(result =>
-		{
-			rwh.Unregister(null);
-			return ctr.Unregister();
-		});
+		tcs.Task.ContinueWith(
+			continuationFunction: result =>
+			{
+				rwh.Unregister(null);
+				return !ctr.Token.CanBeCanceled || ctr.Unregister();
+			},
+			continuationOptions: TaskContinuationOptions.ExecuteSynchronously
+		);
 
 		return tcs.Task;
 	}