How to unit test a Spring MVC controller using @PathVariable?

Question

I have a simple annotated controller similar to this one:

@Controller
public class MyController {
  @RequestMapping("/{id}.html")
  public String doSomething(@PathVariable String id, Model model) {
    // do something
    return "view";
  }
}

and I want to test it with an unit test like this:

public class MyControllerTest {
  @Test
  public void test() {
    MockHttpServletRequest request = new MockHttpServletRequest();
    request.setRequestURI("/test.html");
    new AnnotationMethodHandlerAdapter()
      .handle(request, new MockHttpServletResponse(), new MyController());
    // assert something
  }
}

The problem is that AnnotationMethodHandlerAdapter.handler() method throws an exception:

java.lang.IllegalStateException: Could not find @PathVariable [id] in @RequestMapping
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter$ServletHandlerMethodInvoker.resolvePathVariable(AnnotationMethodHandlerAdapter.java:642)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolvePathVariable(HandlerMethodInvoker.java:514)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:262)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:146)

Answer 1

I'd call what you're after an integration test based on the terminology in the Spring reference manual. How about doing something like:

import static org.springframework.test.web.ModelAndViewAssert.*;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({/* include live config here
    e.g. "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;
    private MyController controller;

    @Before
    public void setUp() {
       request = new MockHttpServletRequest();
       response = new MockHttpServletResponse();
       handlerAdapter = applicationContext.getBean(HandlerAdapter.class);
       // I could get the controller from the context here
       controller = new MyController();
    }

    @Test
    public void testDoSomething() throws Exception {
       request.setRequestURI("/test.html");
       final ModelAndView mav = handlerAdapter.handle(request, response, 
           controller);
       assertViewName(mav, "view");
       // assert something
    }
}

For more information I've written a blog entry about integration testing Spring MVC annotations.