Getting blank response in spring rest controller unit test cases

Question

I have written unit test cases for a spring rest controller for below put method

 @PutMapping("/offers/{jobTitle}")
 public Offer updateOffer(@PathVariable String jobTitle,@Valid @RequestBody Offer offer) {          
           return offerService.updateNoOfPost(jobTitle, offer);
  }

Below is my service class

  @Override
    public Offer updateNoOfPost(String jobTitle, Offer offer) {
        if(!offerRepository.existsById(jobTitle))
            throw new ResourceNotFoundException("JobTitle "+jobTitle+" not found !!");
        offer.setNoOfPost(offer.getNoOfPost());
        return offerRepository.save(offer);
    }

I have written the unit test case for this method using testNg and mockito

public class OfferControllerTest {

private MockMvc mvc;
private JacksonTester<Offer> jsonOffer;

@Mock
private OfferService service;

@InjectMocks
OfferController offerController;

private Offer offer;

@BeforeMethod
public void setup() {
    offer = new Offer("LSE", new Date(),1);
     MockitoAnnotations.initMocks(this);
      mvc = MockMvcBuilders.standaloneSetup(offerController)
                .build();

      JacksonTester.initFields(this, new ObjectMapper());
}
   @Test
   public void updateOffer() throws  Exception {
       Mockito.when(service.updateNoOfPost("LSE", offer)).thenReturn(offer);
       MockHttpServletResponse response = mvc.perform(
               put("/offers/LSE").contentType(MediaType.APPLICATION_JSON).content(
                       jsonOffer.write(new Offer("SE", new Date(), 19)).getJson()
               )).andReturn().getResponse();
       assertThat(response.getContentAsString()).isEqualTo(new ObjectMapper().writeValueAsString(offer));
   }

I am getting response code as 200. but getting blank body.pls find error below

FAILED: updateOffer
org.junit.ComparisonFailure: expected:<"[{"jobTitle":"LSE","createdAt":"2018-10-27","noOfPost":1}]"> but was:<"[]">
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

what am i missing ? is this the standard way of writting unit test cases for spring rest controller ?

Answer 1

Below mocking should fix the issue

Mockito.when(service.updateNoOfPost(Mockito.any(String.class), Mockito.any())).thenReturn(offer);

Read more here: stack-46914252