Unit testing spring boot controller with Mockito

I have the following controller:

@RestController
@RequestMapping("cats")
public class CatController {
    private IDatabaseCatDao databaseCatService;
    private DataValidator catDataValidator;

    public CatController(IDatabaseCatDao databaseCatService, DataValidator catDataValidator) {
        this.databaseCatService = databaseCatService;
        this.catDataValidator = catDataValidator;
    }

    @PostMapping
    public ResponseEntity addCat(@RequestBody Cat cat) {
        catDataValidator.validateCatAdding(cat, cats);
        databaseCatService.addCat(cat);
        URI location = ServletUriComponentsBuilder.fromCurrentRequest().buildAndExpand(cat.getName()).toUri();
        return ResponseEntity.created(location).build();
    }
}    

catDataValidator - check if data is correct
databaseCatService - insert in database + caching locally

I need to test It using jUnit and Mockito.

My test class is following:

@RunWith(SpringRunner.class)
@WebMvcTest(value = CatController.class, secure = false)
public class CatControllerTest {
    @Autowired
    private MockMvc mockMvc;

    @MockBean
    private IDatabaseCatDao databaseCatService;

    private String catExampleJson = "..some json file..";

   public void addCat() throws Exception {
        Mockito.doNothing().when(databaseCatService).addCat(Mockito.any(Cat.class));
        RequestBuilder requestBuilder = MockMvcRequestBuilders
                .post("/cats")
                .accept(MediaType.APPLICATION_JSON).content(catExampleJson)
                .contentType(MediaType.APPLICATION_JSON);
        MvcResult result = mockMvc.perform(requestBuilder).andReturn();
        MockHttpServletResponse response = result.getResponse();
        assertEquals(HttpStatus.CREATED.value(), response.getStatus());
    }
}

Mockito.doNothing() because service addCat() is void method.
Validation I should better test separetely
Cats map I don't use here

java.lang.Exception: No runnable methods

update:

It can be something wrong with my dependencies, i am searching ..