Unit testing controllers with annotations

Question

Hi there,

I'm trying to write some unit tests for my controllers in a Spring MVC web app. I have already got a fairly comprehensive set of unit tests for the domain model, but for completeness I want to test the controllers too.

The issue I'm facing is trying to test them without loading a Spring context. I thought I could get around this with mocking, but the method in the controller has a @Transactional annotation which attempts to open a transaction (and fails with a NullPointerException because no Spring context is loaded).

Code example:

public class UsersController {

  @Autowired private UserManager userManager;

  @Transactional
  @RequestMapping(method = RequestMethod.POST)
  public ModelAndView create(User user) {

    userManager.save(user);

    ModalAndView mav = new ModelAndView();    
    mav.addObject("user", user);
    mav.setViewName("users/view");
    return mav;
  }

}

So essentially I want to test the behaviour without loading a context and actually persisting the user.

Does anyone have any ideas on how I can achieve this?

Cheers,

Caps

Answer 1

I'd say mocking is the way to go here. The @Transactional annotation will have no effect unless there is a Spring context loaded and instructed to configure annotation-based transactions.

Make sure that you aren't instructing JUnit to run your test within a spring context by specifying something like:

@ContextConfiguration(locations = "classpath:spring/ITestAssembly.xml")
@RunWith(SpringJUnit4ClassRunner.class)

To prevent confusion, I keep my unit tests (not running in a spring context) in separate files than my integration tests. Typically all mocking occurs in the unit tests and not in integration tests.

Answer 2

The NullPointerException occurs not because of the Transactional, but because nothing gets injectedas UserManager. You have two options:

• run with the spring test runner
• mock the userManager and set it.