anchor.diff:        // given
         connection.when(callsTo('sendRequest')).thenCall((_) {
           defaultCommunicator.stop();
  -        return new Future.value(response_data);
  +        return new Future.value(data);
         });
         defaultCommunicator = new Communicator(connection, 'months', handleData,
             handleDiff);
  
positive.code:     test("get_diff sent with proper version number.", () {
        // given
        connection.when(callsTo('sendRequest')).thenCall((_) {
          return new Future.value(response_data);
        }).thenCall((_) {
          defaultCommunicator.stop();
          return new Future.value(empty_diff);
        });
        defaultCommunicator = new Communicator(connection, 'months', handleData,
            handleDiff);
  
negative.code:         handleData, handleDiff, 'diff');
      Communicator dataCommunicator = new Communicator(connection, 'months',
          handleData, handleDiff, 'data');
      Map data, diff, emptyDiff;
  
      setUp(() {
        connection = new ConnectionMock();
        handleData = new FunctionMock();
        handleDiff = new FunctionMock();
        data = {'data': 'some_data', 'version': 12};
        diff = {'diff': [{'version': 13}, {'version': 14}]};
        emptyDiff = {'diff': []};
      });
  
      test("get_data sent after start.", () {
        // given
        connection.when(callsTo('sendRequest')).thenCall((_) {
          defaultCommunicator.stop();
          return new Future.value(data);
        });
        handleData = new FunctionMock();
        defaultCommunicator = new Communicator(connection, 'months', handleData,
  