StepManager extends Observable implements MessageListener { protected void onError(ProcessingError processingError) { setChanged(); notifyObservers(new ProcessingErrorMessage(processingError, correlationId)); } StepManager(TimeoutWatch timeoutWatch, JmsConnection jmsConnection, String correlationId,
      long messageTimeToLive); void closeConnections(); int getTotalTasksCount(); ProgressLog getProgress();  }
@Test public void onError_verifyObserversNotified() throws Exception { tested.onError(ProcessingError.collectingError("test")); verify(observer, times(1)).update(Matchers.<Observable>any(), any()); }