anchor.diff:   */
   
   class Configuration {
  +  // The VM won't shut down if a receive port is open. Use this to make sure
  +  // we correctly wait for asynchronous tests.
  +  ReceivePort _receivePort;
     TestCase currentTestCase = null;
   
     /**
  
positive.code: 
      if (success) {
        _postMessage('unittest-suite-success');
      } else {
        throw new Exception('Some tests failed.');
      }
  
negative.code:    * wait until they are done.
     */
    void onStart() {
      _receivePort = new ReceivePort();
      _postMessage('unittest-suite-wait-for-done');
    }
  
  