Question

Please, help me understand the following.

I have an spring integration test, which I’m trying to test the method of ProcessCommentsDao class :

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = {"classpath:testContext.xml"})
@Transactional()
public class ParseCommentsTest {

  @Resource
  private ProcessCommentsDao processCommentsDao;

  @Test
  public void testJMS() throws Exception {

     // Test data creation
     .........................

     processCommentsDao.parseComments();
   }
 }

In the method parseComments(), I get a list of entities, then each entity are processed through the Spring’s JMS MessageListener implementation:

@Service
public class ProcessCommentsDaoImpl extends BaseDao implements IProcessCommentsDao {

    private static final int PARSE_COMMENTS_COUNT_LIMIT = 100;
    @Autowired
    private JmsTemplate jmsTemplate;
    @Autowired
    private Queue parseCommentsDestination;

    @Override
    public void parseComments() {

      List<Comment> comments = attributeDao.findTopUnparsedComments(PARSE_COMMENTS_COUNT_LIMIT);

      for (Comment comment : comments) {
        jmsTemplate.convertAndSend(parseCommentsDestination, comment);
      }
    }
}

Implementation of the MessageListener as follows:

@Component
public class QueueListener implements MessageListener {

  @PersistenceContext
  private  EntityManager em;

  @Transactional()
  public void onMessage(final Message message) {
      try {
         if (message instanceof ObjectMessage) {
            final ObjectMessage objMessage = (ObjectMessage) message;
            Comment comment = (Comment) objMessage.getObject();

            //...Some logic ...

             comment = em.find(Comment.class, comment.getId());
             comment.setPosStatus(ParsingType.PROCESSED);
             em.merge(comment);

              //...Some logic ...

    } catch (final JMSException e) {
        e.printStackTrace();
    }
}

}

As a result, the method em.find (Comment.class, comment.getId ()) returns null, because the data were created in another thread and the current thread does not know anything about this transaction. Is there a way to set up a transaction propagation so that MessageListener method seen entyties who were created in the main thread, in which the test method run?

Answer 1

As a result, the method em.find (Comment.class, comment.getId ()) returns null, because the data were created in another thread and the current thread does not know anything about this transaction.

To be more exact, the message listener runs in a separate transaction, and it doesn’t see the data created by ParseCommentsTest.testJMS because that method did not commit.

What’s more important, your test is not written correctly. It has a race condition: the calls to jmsTemplate.convertAndSend() are asynchronous, so the logic in QueueListener.messageListener() may be invoked after the test method completes (and rolls back the changes it has made). This test may yield different results each time it’s run.

Your code is not easily testable, either. Consider extracting processing logic from the onMessage() method to a POJO and test it separately.