Mock test for a Spring controller

Having built a simple Spring Web App, now I want to test its only controller. In the previous post I have done it "by hand", running a browser on its url and verifying that I actually get the expected page, now I use the mock testing support provided by the Spring framework.

Firstly I add to the pom file the Spring test dependency:
 <!-- ... -->
 <!-- ... -->
 <!-- ... -->
 <!-- ... -->
Then I write a JUnit tester for my HomeController, following a simple pattern:
public void testHome() {
    HomeController controller = new HomeController();  // 1
    try {
        MockMvc mockMvc = standaloneSetup(controller).build();  // 2
        mockMvc.perform(get("/")).andExpect(view().name("home"));  // 3
    } catch(Throwable t) {  // 4
        // ...
1. I create an object from my controller.
2. I build a mock MVC test object from my controller.
3. I perform a mock HTTP GET command for "/" and verify I get back a view named "home".
4. There is not much control on what a MockMvc would throw in case something goes wrong, we have to be ready to catch any possible throwable.

It looks very clean and simple. However I had a problem in the form of this exception:
java.lang.NoClassDefFoundError: javax/servlet/SessionCookieConfig at
The fact is that I specified in the POM a dependency for the ancient javax.servlet servlet-api 2.5, while I should use at least a version 3 to get the job done. For my purposes, 3.1.0 is more than enough.
Pay attention to the artifact name change that happened right at the time of moving from 2 to 3. Now the servlet api is identified by the id javax.servlet-api.

Let's slightly improve my web app. We want now that the controller returns the home view while getting both root and "/homepage".

I add another test case, testHomeExtra(), that is just like testHome() but it performs a GET on the other URI.
As expected, it fails, giving as reason, "No ModelAndView found".

I change my controller, specifying at class level which URI's it has to manage:
@RequestMapping({"/", "/homepage"})
public class HomeController {
    @RequestMapping(method = GET)
    public String home(Model model) {
        return "home";
And now I have green light while testing.
Reference: Building Spring web applications, from Spring in Action, Fourth Edition by Craig Walls. Chapter five, section two, Testing the controller.

I have committed the project changes to GitHub.

No comments:

Post a Comment