anchor.diff:     * wait until they are done.
      */
     void onStart() {
  +    _receivePort = new ReceivePort();
       _postMessage('unittest-suite-wait-for-done');
     }
   
  
positive.code: 
      if (success) {
        _postMessage('unittest-suite-success');
      } else {
        throw new Exception('Some tests failed.');
      }
  
negative.code:  */
  
  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;
  
    /**
  