I'm trying to test my rest controller. No issues with GETs, but when I try to test a POST method I'm unable to attach the body.

private static final MediaType contentType = new MediaType(MediaType.APPLICATION_JSON.getType(),
                                                            MediaType.APPLICATION_JSON.getSubtype(),
                                                            Charset.forName("utf8"));
private ObjectMapper jsonMapper = new ObjectMapper().setSerializationInclusion(JsonInclude.Include.NON_NULL);

@Test
public void test1() throws Exception {
    //...Create DTO
    //...Create same pojo but as entity

    when(serviceMock.addEntity(e)).thenReturn(e);

    mvc.perform(post("/uri")
        .contentType(contentType)
        .content(jsonMapper.writeValueAsString(dto))
        )
        .andDo(print())
        .andExpect(status().isCreated())
        .andExpect(content().contentType(contentType)); //fails because there is no content returned
}

This is the request output:

MockHttpServletRequest:
      HTTP Method = POST
      Request URI = /uri
       Parameters = {}
          Headers = {Content-Type=[application/json;charset=UTF-8]}

There is no body. Why? I have printed jsonMapper.writeValueAsString(dto) and is not null.

edit:

Adding controller code:

@RestController
@RequestMapping("/companies")
public class CompanyController {

    @Autowired
    private CompanyService service;
    @Autowired
    private CompanyMapper mapper;



    @RequestMapping(method=RequestMethod.GET)
    public List<CompanyDTO> getCompanies() {
        List<Company> result = service.getCompanies();
        return mapper.toDtoL(result);
    }   

    @RequestMapping(method=RequestMethod.POST)
    @ResponseStatus(HttpStatus.CREATED)
    public CompanyDTO createCompany(@RequestBody @Valid CompanyDTO input) {
        Company inputE = mapper.toEntity(input);
        Company result = service.addCompany(inputE);
        return mapper.toDto(result);
    }