java - Testing Spring MVC annotation mappings

Question

With Spring MVC, you can specify that a particular URL will handled by a particular method, and you can specify that particular parameters will map to particular arguments, like so:

@Controller
public class ImageController {

   @RequestMapping("/getImage")
   public String getImage( @RequestParam("imageId") int imageId, Map<String,Object> model ) {
      model.put("image",ImageService.getImage(imageId));
   }

}

This is all well and good, but now I want to test that an http request with an imageId parameter will invoke this method correctly. In other words, I want a test that will break if I remove or change any of the annotations. Is there a way to do this?

It is easy to test that getImage works correctly. I could just create an ImageController and invoke getImage with appropriate arguments. However, this is only one half of the test. The other half of the test must be whether getImage() will be invoked by the Spring framework when an appropriate HTTP request comes in. I feel like I also need a test for this part, especially as my @RequestMapping annotations become more complex and invoke complex parameter conditions.

Could you show me a test that will break if I remove line 4, @RequestMapping("getImage")?

Answer 1

You could use AnnotationMethodHandlerAdapter and its handle method programmatically. This will resolve the method for the given request and execute it. Unfortunately this is a little indirect. Actually there is a private class called ServletHandlerMethodResolver in AMHA that is responsible for just resolving the method for a given request. I just filed a request for improvement on that topic, as I really would like to see this possible, too.

In the meantime you could use e.g. EasyMock to create a mock of your controller class, expect the given method to be invoked and hand that mock to handle.

Controller:

@Controller
public class MyController {

  @RequestMapping("/users")
  public void foo(HttpServletResponse response) {

    // your controller code
  }
}

Test:

public class RequestMappingTest {

  private MockHttpServletRequest request;
  private MockHttpServletResponse response;
  private MyController controller;
  private AnnotationMethodHandlerAdapter adapter;


  @Before
  public void setUp() {

    controller = EasyMock.createNiceMock(MyController.class);

    adapter = new AnnotationMethodHandlerAdapter();
    request = new MockHttpServletRequest();
    response = new MockHttpServletResponse();
  }


  @Test
  public void testname() throws Exception {

    request.setRequestURI("/users");

    controller.foo(response);
    EasyMock.expectLastCall().once();
    EasyMock.replay(controller);

    adapter.handle(request, response, controller);

    EasyMock.verify(controller);
  }
}

Regards, Ollie