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

The exception message refers to a "feed" variable, which isn't present in your sample code, it's likely being caused by something you haven't shown us.

Also, your test is testing Spring and your own code. Is this really what you want to do?

It's better to assume that Spring works (which it does), and just test your own class, i.e. call MyController.doSomething() directly. That's one benefit of the annotation approach - you don't need to use mock requests and responses, you just use domain POJOs.

Answer 2

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.

Answer 3

I've found that you can manually insert a PathVariable mapping into the request object. This is distinctly non-ideal but appears to work. In your example, something like:

@Test
public void test() {
    MockHttpServletRequest request = new MockHttpServletRequest();
    request.setRequestURI("/test.html");
    HashMap<String, String> pathvars = new HashMap<String, String>();
    pathvars.put("id", "test");
    request.setAttribute(HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, pathvars);
    new AnnotationMethodHandlerAdapter().handle(request, new MockHttpServletResponse(), new MyController());
   // assert something
}

I'd definitely be interested in finding a better option.

Answer 4

I'm not sure my original answer is going to help with @PathVariable. I've just tried testing an @PathVariable and I get the following exception:

org.springframework.web.bind.annotation.support.HandlerMethodInvocationException: Failed to invoke handler method [public org.springframework.web.servlet.ModelAndView test.MyClass.myMethod(test.SomeType)]; nested exception is java.lang.IllegalStateException: Could not find @PathVariable [parameterName] in @RequestMapping

The reason is that the path variables in the request get parsed by an interceptor. The following approach works for me:

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

@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 testDoSomething() throws Exception {
        request.setRequestURI("/test.html");
        request.setMethod("GET");
        final ModelAndView mav = handle(request, response);
        assertViewName(mav, "view");
        // assert something else
    }

I've add a new blog post on integration testing spring mvc annotations