Merge pull request #137255 from pohly/ktesting-contexthelper-test-fix

Ktesting: contexthelper panic + test fix

test/utils/ktesting/contexthelper.go

@@ -48,11 +48,17 @@ func withTimeout(ctx context.Context, tb TB, timeout time.Duration, timeoutCause
 	cancelCtx, cancel := context.WithCancelCause(ctx)
 	after := time.NewTimer(timeout)
 	stopCtx, stop := context.WithCancel(ctx) // Only used internally, doesn't need a cause.
+	done := make(chan struct{})
 	tb.Cleanup(func() {
 		cancel(cleanupErr(tb.Name()))
 		stop()
+		// Wait for goroutine termination. This is important because
+		// otherwise the goroutine might log through tb *after* the
+		// test has already finished, which causes a panic.
+		<-done
 	})
 	go func() {
+		defer close(done)
 		select {
 		case <-stopCtx.Done():
 			after.Stop()

test/utils/ktesting/contexthelper_test.go

@@ -119,7 +119,11 @@ func TestCause(t *testing.T) {
 						assert.Equal(t, tt.expectDeadline, time.Until(actualDeadline), "remaining time till Deadline()")
 					}
 				}
+				// Unblock background goroutines.
 				time.Sleep(tt.sleep)
+				// Wait for them to do their work.
+				synctest.Wait()
+				// Now check.
 				actualErr := ctx.Err()
 				actualCause := context.Cause(ctx)
 				assert.Equal(t, tt.expectErr, actualErr, "ctx.Err()")