Fix timeout check in WithResult extension

Src/FluentAssertions/AsyncAssertionsExtensions.cs

@@ -18,6 +18,12 @@ public static class AsyncAssertionsExtensions
     /// <param name="becauseArgs">
     /// Zero or more objects to format using the placeholders in <paramref name="because"/>.
     /// </param>
+    /// <remarks>
+    /// Please note that this assertion cannot identify whether the previous assertion was successful or not.
+    /// In case it was not successful and it is running within an active <see cref="FluentAssertions.Execution.AssertionScope"/>
+    /// there is no current result to compare with.
+    /// So, this extension will compare with the default value.
+    /// </remarks>
     public static async Task<AndWhichConstraint<GenericAsyncFunctionAssertions<T>, T>> WithResult<T>(
         this Task<AndWhichConstraint<GenericAsyncFunctionAssertions<T>, T>> task,
         T expected, string because = "", params object[] becauseArgs)

Src/FluentAssertions/Specialized/GenericAsyncFunctionAssertions.cs

@@ -51,13 +51,13 @@ public GenericAsyncFunctionAssertions(Func<Task<TResult>> subject, IExtractExcep
             if (success)
             {
                 bool completesWithinTimeout = await CompletesWithinTimeoutAsync(task, remainingTime);
-                Execute.Assertion
-                    .ForCondition(completesWithinTimeout)
-                    .BecauseOf(because, becauseArgs)
-                    .FailWith("Expected {context:task} to complete within {0}{reason}.", timeSpan);
-            }
+                success = Execute.Assertion
+                .ForCondition(completesWithinTimeout)
+                .BecauseOf(because, becauseArgs)
+                .FailWith("Expected {context:task} to complete within {0}{reason}.", timeSpan);
+        }
 
-            TResult result = task.IsCompleted ? task.Result : default;
+            TResult result = success ? task.Result : default;
             return new AndWhichConstraint<GenericAsyncFunctionAssertions<TResult>, TResult>(this, result);
         }
 

Tests/FluentAssertions.Specs/FakeClock.cs

@@ -9,7 +9,7 @@ namespace FluentAssertions.Specs;
 /// Implementation of <see cref="IClock"/> for testing purposes only.
 /// </summary>
 /// <remarks>
-/// It allows you to control the "current" time.
+/// It allows you to control the "current" date and time for test purposes.
 /// </remarks>
 internal class FakeClock : IClock
 {
@@ -25,17 +25,26 @@ Task IClock.DelayAsync(TimeSpan delay, CancellationToken cancellationToken)
 
     public ITimer StartTimer() => new TestTimer(() => elapsedTime);
 
+    /// <summary>
+    /// Advances the internal clock.
+    /// </summary>
     public void Delay(TimeSpan timeToDelay)
     {
         elapsedTime += timeToDelay;
     }
 
+    /// <summary>
+    /// Simulates the completion of the pending delay task.
+    /// </summary>
     public void Complete()
     {
         // the value is not relevant
         delayTask.SetResult(true);
     }
 
+    /// <summary>
+    /// Simulates the completion of the pending delay task after the internal clock has been advanced.
+    /// </summary>
     public void CompleteAfter(TimeSpan timeSpan)
     {
         Delay(timeSpan);

Tests/FluentAssertions.Specs/Specialized/TaskOfTAssertionSpecs.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Diagnostics.CodeAnalysis;
 using System.Threading.Tasks;
 using FluentAssertions.Execution;
 using FluentAssertions.Extensions;
@@ -10,6 +9,8 @@
 using Xunit;
 using Xunit.Sdk;
 
+using static FluentAssertions.FluentActions;
+
 namespace FluentAssertions.Specs.Specialized;
 
 public static class TaskOfTAssertionSpecs
@@ -165,6 +166,28 @@ public async Task When_task_completes_late_it_in_assertion_scope_should_fail()
             await action.Should().ThrowAsync<XunitException>();
         }
 
+        [Fact]
+        public async Task When_task_does_not_complete_the_result_extension_does_not_hang()
+        {
+            // Arrange
+            var timer = new FakeClock();
+            var taskFactory = new TaskCompletionSource<int>();
+
+            // Act
+            Func<Task> action = () =>
+            {
+                Func<Task<int>> func = () => taskFactory.Task;
+                using var _ = new AssertionScope();
+                return func.Should(timer).CompleteWithinAsync(100.Milliseconds()).WithResult(2);
+            };
+            timer.Complete();
+
+            // Assert
+            var assertionTask = action.Should().ThrowAsync<XunitException>()
+                .WithMessage("Expected*to complete within 100ms.*Expected return*to be 2, but found 0.");
+            await Awaiting(() => assertionTask).Should().CompleteWithinAsync(200.Seconds());
+        }
+
         [Fact]
         public async Task When_task_consumes_time_in_sync_portion_it_should_fail()
         {

docs/_pages/releases.md

@@ -12,6 +12,7 @@ sidebar:
 ### What's new
 
 ### Fixes
+* Fixed hanging of `CompleteWithinAsync` when used with `WithResult` and `AssertionScope` - [#2101](https://github.com/fluentassertions/fluentassertions/pull/2101)
 
 * `BeEquivalentTo` no longer crashes on fields hiding base-class fields - [#1990](https://github.com/fluentassertions/fluentassertions/pull/1990)