fix: prevent test hangs when shared IAsyncDiscoveryInitializer partially initializes then throws

TUnit.Core/ObjectInitializer.cs

@@ -123,9 +123,10 @@ private static async ValueTask InitializeCoreAsync(
         }
         catch
         {
-            // Remove failed initialization from cache to allow retry
-            // This is important for transient failures that may succeed on retry
-            InitializationTasks.TryRemove(obj, out _);
+            // Do NOT remove from cache - the faulted Lazy<Task> stays so subsequent
+            // callers get the same error immediately via .WaitAsync() on the faulted task.
+            // Removing and retrying can cause hangs when InitializeAsync partially initialized
+            // resources (e.g. started ports/processes) that block re-initialization (#4715).
             throw;
         }
     }

TUnit.Engine.Tests/AttributePropertyInjectionFailureTests.cs

@@ -0,0 +1,21 @@
+using Shouldly;
+using TUnit.Engine.Tests.Enums;
+
+namespace TUnit.Engine.Tests;
+
+public class AttributePropertyInjectionFailureTests(TestMode testMode) : InvokableTestBase(testMode)
+{
+    [Test]
+    public async Task Test()
+    {
+        await RunTestsWithFilter(
+            "/*/*/AttributePropertyInjectionFailureTests/*",
+            [
+                result => result.ResultSummary.Outcome.ShouldBe("Failed"),
+                result => result.ResultSummary.Counters.Total.ShouldBe(1),
+                result => result.ResultSummary.Counters.Passed.ShouldBe(0),
+                result => result.ResultSummary.Counters.Failed.ShouldBe(1),
+                result => result.ResultSummary.Counters.NotExecuted.ShouldBe(0)
+            ]);
+    }
+}

TUnit.Engine/Services/ObjectLifecycleService.cs

@@ -329,7 +329,7 @@ public async ValueTask<T> EnsureInitializedAsync<T>(
         // Fast path: already processed by this service
         if (_initializationTasks.TryGetValue(obj, out var existingTcs) && existingTcs.Task.IsCompleted)
         {
-            if (existingTcs.Task.IsFaulted)
+            if (existingTcs.Task.IsFaulted || existingTcs.Task.IsCanceled)
             {
                 await existingTcs.Task.ConfigureAwait(false);
             }
@@ -353,16 +353,17 @@ public async ValueTask<T> EnsureInitializedAsync<T>(
             }
             catch (OperationCanceledException)
             {
-                // Propagate cancellation without caching failure - allows retry after cancel
-                _initializationTasks.TryRemove(obj, out _);
+                // Do NOT remove from cache - the cancelled TCS stays so subsequent
+                // callers get the cancellation immediately. Retrying can cause hangs
+                // when InitializeAsync partially initialized resources (#4715).
                 tcs.SetCanceled();
                 throw;
             }
             catch (Exception ex)
             {
-                // Remove failed initialization from cache to allow retry
-                // This is important for transient failures that may succeed on retry
-                _initializationTasks.TryRemove(obj, out _);
+                // Do NOT remove from cache - the faulted TCS stays so subsequent
+                // callers get the same error immediately. Retrying can cause hangs
+                // when InitializeAsync partially initialized resources (#4715).
                 tcs.SetException(ex);
                 throw;
             }

TUnit.Engine/TestDiscoveryService.cs

@@ -81,11 +81,15 @@ public async Task<TestDiscoveryResult> DiscoverTests(string testSessionId, ITest
             var metadataToInclude = _dependencyExpander.ExpandToIncludeDependencies(allMetadataList, filter);
 
             // Build tests directly from the pre-collected metadata (avoid re-collecting)
+            // Apply 5-minute discovery timeout matching the streaming path (#4715)
+            using var filterCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+            filterCts.CancelAfter(TimeSpan.FromMinutes(5));
+
             var buildingContext = new Building.TestBuildingContext(isForExecution, Filter: null);
             var tests = await _testBuilderPipeline.BuildTestsFromMetadataAsync(
                 metadataToInclude,
                 buildingContext,
-                cancellationToken).ConfigureAwait(false);
+                filterCts.Token).ConfigureAwait(false);
 
             var testsList = tests.ToList();