Testing Spring @MVC annotations

Question

I ran into a problem the other day where a @Valid annotation was accidentally removed from a controller class. Unfortunately, it didn't break any of our tests. None of our unit tests actually exercise the Spring AnnotationMethodHandlerAdapter pathway. We just test our controller classes directly.

How can I write a unit or integration test that will correctly fail if my @MVC annotations are wrong? Is there a way I can ask Spring to find and exercise the relevant controller with a MockHttpServlet or something?

Answer 1

I write integration tests for this kind of thing. Say you have a bean with validation annotations:

public class MyForm {
    @NotNull
    private Long myNumber;

    ...
}

and a controller that handles the submission

@Controller
@RequestMapping("/simple-form")
public class MyController {
    private final static String FORM_VIEW = null;

    @RequestMapping(method = RequestMethod.POST)
    public String processFormSubmission(@Valid MyForm myForm,
            BindingResult result) {
        if (result.hasErrors()) {
            return FORM_VIEW;
        }
        // process the form
        return "success-view";
    }
}

and you want to test that the @Valid and @NotNull annotations are wired correctly:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"file:web/WEB-INF/application-context.xml",
    "file:web/WEB-INF/dispatcher-servlet.xml"})
public class MyControllerIntegrationTest {

    @Inject
    private ApplicationContext applicationContext;

    private MockHttpServletRequest request;
    private MockHttpServletResponse response;
    private HandlerAdapter handlerAdapter;

    @Before
    public void setUp() throws Exception {
        this.request = new MockHttpServletRequest();
        this.response = new MockHttpServletResponse();

        this.handlerAdapter = applicationContext.getBean(HandlerAdapter.class);
    }

    ModelAndView handle(HttpServletRequest request, HttpServletResponse response)
            throws Exception {
        final HandlerMapping handlerMapping = applicationContext.getBean(HandlerMapping.class);
        final HandlerExecutionChain handler = handlerMapping.getHandler(request);
        assertNotNull("No handler found for request, check you request mapping", handler);

        final Object controller = handler.getHandler();
        // if you want to override any injected attributes do it here

        final HandlerInterceptor[] interceptors =
            handlerMapping.getHandler(request).getInterceptors();
        for (HandlerInterceptor interceptor : interceptors) {
            final boolean carryOn = interceptor.preHandle(request, response, controller);
            if (!carryOn) {
                return null;
            }
        }

        final ModelAndView mav = handlerAdapter.handle(request, response, controller);
        return mav;
    }

    @Test
    public void testProcessFormSubmission() throws Exception {
        request.setMethod("POST");
        request.setRequestURI("/simple-form");
        request.setParameter("myNumber", "");

        final ModelAndView mav = handle(request, response);
        // test we're returned back to the form
        assertViewName(mav, "simple-form");
        // make assertions on the errors
        final BindingResult errors = assertAndReturnModelAttributeOfType(mav, 
                "org.springframework.validation.BindingResult.myForm", 
                BindingResult.class);
        assertEquals(1, errors.getErrorCount());
        assertEquals("", errors.getFieldValue("myNumber"));        
    }

See my blog post on integration testing Spring's MVC annotations