Spring MVC - Unit Testing

Spring MVC Test Framework is build on Servlet API mock objects (also provided by Spring in package: org.springframework.mock.web) and hence does not use a running Servlet container.

Prepare the test class

We have to use three annotations in our test class as shown:

import org.junit.runner.RunWith;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
import org.springframework.test.context.web.WebAppConfiguration;
import org.springframework.test.context.ContextConfiguration;

@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextConfiguration(classes = MyWebConfig.class)
public class MyMvcControllerTest {
....
}

@RunWith is a JUnit annotation, which can be used to replace default test runner org.junit.runners.BlockJUnit4ClassRunner.

SpringJUnit4ClassRunner extends default test runner BlockJUnit4ClassRunner

@WebAppConfiguration is used to specify that WebApplicationContext should be loaded for the test.

@ContextConfiguration is to used to specify how to load spring bean metadata. In above example we are loading it from our @Configuration annotated class MyWebConfig

Setting up @Before objects

In @Before method, we need to initialize Spring specific mock object: MockMvc which is the main entry point for server-side Spring MVC test support.

  public class MyMvcControllerTest {

    @Autowired
    private WebApplicationContext wac;
    private MockMvc mockMvc;

    @Before
    public void setup() {
        DefaultMockMvcBuilder builder = MockMvcBuilders.webAppContextSetup(this.wac);
        this.mockMvc = builder.build();
    }

MockMvcBuilders is the main class to to access a specific implementation of MockMvcBuilder (an interface).

Write @Test Method

Here we have to take help of two builder classes:

MockMvcRequestBuilders: This class helps building MockHttpServletRequest

MockMvcResultMatchers: This class helps building a ResultMatcher which matches the result of an executed request against some expectation.

   @Test
   public void testMyMvcController() throws Exception {
       ResultMatcher ok = MockMvcResultMatchers.status().isOk();
       ResultMatcher msg = MockMvcResultMatchers.model()
                           .attribute("msg", "Spring quick start!!");

       MockHttpServletRequestBuilder builder = MockMvcRequestBuilders.get("/");
       this.mockMvc.perform(builder)
                   .andExpect(ok)
                   .andExpect(msg);
    }

Here is our controller:

@Controller
public class MyMvcController {

    @RequestMapping(value = "/", method = RequestMethod.GET)
    public String prepareView(Model model) {
        model.addAttribute("msg", "Spring quick start!!");
        return "my-page";
    }
}

Example Project

Dependencies and Technologies Used:

• Spring Web MVC 4.2.4.RELEASE: Spring Web MVC.
• Java Servlet API 3.0.1
• Spring TestContext Framework 4.2.4.RELEASE: Spring TestContext Framework.
• JUnit 4.12: JUnit is a unit testing framework for Java, created by Erich Gamma and Kent Beck.
• JDK 1.8
• Maven 3.0.4