Spring Mockmvc ignores unknown fields

Question

The API method has already been validated with @Valid annotation. When I test this method using postman, and post an unknown field, it works, and rejects the request. However, when I test this using mockMvc, mockMvc ignores unknown fields. Any idea how I can enforce mockMvc to consider the validation in the API method.

Controller

@PostMapping(value = "/path", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<String> notification(@Valid @RequestBody RequestClass requestPayload) {

}

Test method

MockHttpServletRequestBuilder builder = MockMvcRequestBuilders
                .post("/path" )
                
                .content("{\"fakeField\":\"fake\",\"userId\":\"clientId\"")
                .contentType(MediaType.APPLICATION_JSON_VALUE);

        String responseMessage = "Error message";

        this.mockMvc =
                standaloneSetup(myController)
                .build();

        this.mockMvc
                .perform(builder)
                .andDo(print())
                .andExpect(status().is(HttpStatus.BAD_REQUEST.value()))
                .andExpect(content().string(containsString(responseMessage)));

Answer 1

Checking for unknown fields and returning a 400 ( BAD_RQUEST ) is a deserialization feature of Jackson (the ObjectMapper ). It's not handled by Java's Bean Validation.

With your custom MockMvc standalone setup you opt-out of the default Spring Boot auto-configuration which would configure the ObjectMapper according to your configured features.

I'd recommend using @WebMvcTest(YourController.class) for your controller tests and then inject the auto-configured MockMvc :

@WebMvcTest(YourController.class) // auto-configures everything in the background for your, including the ObjectMapper
class YourControllerTest {

  @Autowired
  private MockMvc mockMvc;


}