JAVA - Getting empty MockHttpServletResponse: body..However it's 200

Question

I have written unit test cases for a spring rest controller but I'm getting blank response body.

Below is my controller class

@RestController
@RequestMapping("/v2")

public class controller {

@Autowired

Service service;

@RequestMapping(value="/health",method=RequestMethod.POST)

public String postRequest(@RequestHeader @NotNull@NotBlank String 
transID) {

 return service.getTest(transID); }
}

Below is my service class

 @Component
 public class Service {

 public String getTest(@NotNull String transid) {

 return "Hello World Test";
  } }

Below is my Unit Test class.I have written the unit test case for this method using mockito

 class UnitTest {
 @InjectMocks

 controller controllerUse;
 @Mock

 Service service;
 @Autowired

  MockMvc mockMvc;

  @BeforeEach

  public void test() {

  MockitoAnnotations.initMocks(this);

  mockMvc=MockMvcBuilders.standaloneSetup(controllerUse).build();

   }

   @Test

   public void confirmTest() throws Exception {

   mockMvc.perform(post("/v2/health")

   .header("transID","ABC"))

   .andExpect(status().isOk())

   .andDo(print())

   .andReturn();   }

    }

The OutPut:

MockHttpServletResponse:

Status = 200

Error message = null

Headers = []

Content type = null

Body =

Forwarded URL = null

Redirected URL = null

Cookies = []

I am getting response code as 200. but getting blank body.what am i missing? is this the standard way of writing unit test cases for spring rest controller?

Answer 1

Since you are injecting mock bean service, you need to mock method with your expected response.

Here is sample code using Junit 5 and Spring Boot Test artifact but you can achieve same using standard spring test module as well.

@WebMvcTest(SampleController.class)
class SampleControllerTest {

    @MockBean
    Service service;
    @Autowired
    private MockMvc mockMvc;

    @Test
    public void confirmTest() throws Exception {

        when(service.getTest("ABC")).thenReturn("Hello World");

        mockMvc.perform(post("/v2/health")

                            .header("transID", "ABC"))

               .andExpect(status().isOk())
               .andDo(print())
               .andReturn();
    }
}