MockMvc throws HttpMediaTypeNotSupportedException Status expected: 201 but was 415

Question

I'm testing an api endpoint and MockMvc throws org.springframework.web.HttpMediaTypeNotSupportedException Status expected:<201> but was:<415> Read all SO about similar problems - always solution is in content-type, but not in this case ) What is strange, I cannot see in MockHttpServletResponse's headers application/json.

Controller:

public static final String MEDIA_TYPE_APPLICATION_JSON_UTF8 = "application/json;charset=utf-8";
@PostMapping(value = "/api/Register", consumes = MEDIA_TYPE_APPLICATION_JSON_UTF8, produces = MEDIA_TYPE_APPLICATION_JSON_UTF8)
public ResponseEntity<Map<String, String>> register(@RequestBody Map<String, String> jsonMap) {
  ...
  Map<String, String> responseMap = new HashMap<>();
  MediaType MEDIA_TYPE_JSON_UTF8 = new MediaType("application", "json", StandardCharsets.UTF_8);
  HttpHeaders headers = new HttpHeaders();
  headers.setAccept(Arrays.asList(MEDIA_TYPE_JSON_UTF8));
  headers.setContentType(MEDIA_TYPE_JSON_UTF8);
  ...
  return new ResponseEntity<>(new Gson().toJson(responseMap), headers, HttpStatus.CREATED);
}

Test:

@Test
void Register_phoneNumber_returnOk() throws Exception {
  Map<String, String> body = new HashMap<>();
  body.put("phone", "1112223344");
  Gson gson = new Gson();
  String json = gson.toJson(body);
  MockHttpServletRequestBuilder request = post("/api/Register");
  request.content("{\"phone\":\"1112223344\"}");
  request.accept(MEDIA_TYPE_APPLICATION_JSON_UTF8);
  request.contentType(MEDIA_TYPE_APPLICATION_JSON_UTF8);
  mockMvc.perform(request)
                .andDo(print())
                .andExpect(status().isCreated());
}

Error:

WARN 6188 --- [main] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.HttpMediaTypeNotSupportedException: Content type 'application/json;charset=utf-8' not supported]

    MockHttpServletRequest:
          HTTP Method = POST
          Request URI = /api/Register
           Parameters = {}
              Headers = [Content-Type:"application/json;charset=utf-8", Accept:"application/json;charset=utf-8"]
                 Body = {"phone":"1112223344"}
        Session Attrs = {}

    Handler:
                 Type = ru.controllers.MainController
               Method = ru.controllers.MainController#Register(Map)

    Async:
        Async started = false
         Async result = null

    Resolved Exception:
                 Type = org.springframework.web.HttpMediaTypeNotSupportedException

    ModelAndView:
            View name = null
                 View = null
                Model = null

    FlashMap:
           Attributes = null

    MockHttpServletResponse:
               Status = 415
        Error message = null
              Headers = [Vary:"Origin", "Access-Control-Request-Method", "Access-Control-Request-Headers", Accept:"application/octet-stream, text/plain, application/xml, text/xml, application/x-www-form-urlencoded, application/*+xml, multipart/form-data, multipart/mixed, */*"]
         Content type = null
                 Body = 
        Forwarded URL = null
       Redirected URL = null
              Cookies = []


    java.lang.AssertionError: Status expected:<201> but was:<415>

Answer 1

Answer was quite simple.

Service with @MockBean annotation in test class was creating entities and saving them to db, then controller was returning entity id, that did NPE in entity.getId() and, of course, HTTP 415 in rest controller's test method. At the same time while testing in real db, postman did not show an error, because service layer always returned real id in .getId() method. After i modified service layer code to check entity for null, problem was gone.