anchor.diff:      ui.window.onDrawFrame = null;
     }
   
  -  FakeAsync _fakeAsync;
  +  FakeAsync _currentFakeAsync; // set from runTest to postTest
     Completer<void> _pendingAsyncTasks;
   
     @override
  
positive.code:     assert(inTest);
      FlutterError.onError = _oldExceptionHandler;
      _pendingExceptionDetails = null;
      _currentTestCompleter = null;
      _parentZone = null;
    }
  }
  
negative.code:   }
  
    Zone _parentZone;
  
    VoidCallback _createTestCompletionHandler(String testDescription, Completer<Null> completer) {
      return () {
        // This can get called twice, in the case of a Future without listeners failing, and then
        // our main future completing.
        assert(Zone.current == _parentZone);
        if (_pendingExceptionDetails != null) {
          debugPrint = debugPrintOverride; // just in case the test overrides it -- otherwise we won't see the error!
          reportTestException(_pendingExceptionDetails, testDescription);
          _pendingExceptionDetails = null;
        }
        if (!completer.isCompleted)
          completer.complete(null);
      };
    }
  
    /// Called when the framework catches an exception, even if that exception is
  