fix: flush console output after test completion to prevent truncation (#4545)

TUnit.Engine/Services/TestExecution/TestCoordinator.cs

@@ -150,6 +150,18 @@ await TimeoutHelper.ExecuteWithTimeoutAsync(
         {
             var cleanupExceptions = new List<Exception>();
 
+            // Flush console interceptors to ensure all buffered output is captured
+            // This is critical for output from Console.Write() without newline
+            try
+            {
+                await Console.Out.FlushAsync().ConfigureAwait(false);
+                await Console.Error.FlushAsync().ConfigureAwait(false);
+            }
+            catch (Exception flushEx)
+            {
+                await _logger.LogErrorAsync($"Error flushing console output for {test.TestId}: {flushEx}").ConfigureAwait(false);
+            }
+
             await _objectTracker.UntrackObjects(test.Context, cleanupExceptions).ConfigureAwait(false);
 
             var testClass = test.Metadata.TestClassType;

TUnit.TestProject/Bugs/Issue4545/OutputTruncationTests.cs

@@ -0,0 +1,40 @@
+namespace TUnit.TestProject.Bugs.Issue4545;
+
+/// <summary>
+/// Tests to reproduce the issue where console output is truncated/missing
+/// when tests complete, especially when they end with Console.Write (no newline).
+/// </summary>
+[NotInParallel]
+public class OutputTruncationTests
+{
+    [Test]
+    public async Task Test1_EndsWithWrite_ShouldCaptureAllOutput()
+    {
+        Console.WriteLine("Test1: Start");
+        Console.WriteLine("Test1: Middle");
+        Console.Write("Test1: End (no newline)"); // This may be lost!
+
+        // Small delay to simulate real work
+        await Task.Delay(10);
+    }
+
+    [Test]
+    public async Task Test2_EndsWithWrite_ShouldCaptureAllOutput()
+    {
+        Console.WriteLine("Test2: Start");
+        Console.WriteLine("Test2: Middle");
+        Console.Write("Test2: End (no newline)"); // This may be lost!
+
+        await Task.Delay(10);
+    }
+
+    [Test]
+    public async Task Test3_EndsWithWriteLine_ShouldCaptureAllOutput()
+    {
+        Console.WriteLine("Test3: Start");
+        Console.WriteLine("Test3: Middle");
+        Console.WriteLine("Test3: End (with newline)"); // This should be captured
+
+        await Task.Delay(10);
+    }
+}

TUnit.TestProject/Bugs/Issue4545/ParallelConsoleOutputTests.cs

@@ -43,4 +43,16 @@ public async Task Test3_ShouldCaptureOnlyOwnOutput()
         await Assert.That(output).DoesNotContain("Test1");
         await Assert.That(output).DoesNotContain("Test2");
     }
+
+    [Test]
+    [Repeat(10)]
+    public async Task Test4_EndingWithoutNewline_ShouldStillCaptureOutput()
+    {
+        Console.WriteLine("Test4-Start");
+        await Task.Delay(10);
+        Console.Write("Test4-End-NoNewline");
+        // Test ends here - the final Write should be flushed by the framework
+        // Note: We check this DURING the test since output is buffered
+        // The framework flush will ensure it's available in test results
+    }
 }