@RunWith(SpringRunner.class)
public class ClientControllerTest {

    @Autowired
    MockMvc mockMvc;

    @MockBean
    CreateClientService createClientServiceMock;

    @Autowired
    ObjectMapper objectMapper;

    @Test
    public void testCreateClientSuccessfully() throws Exception {
        given(createClientServiceMock.createClient("Foo")).willReturn(new       Client("Foo"));

    mockMvc.perform(post("/clients")
        .contentType(MediaType.APPLICATION_JSON)
        .content(objectMapper.writeValueAsBytes(new     CreateClientRequest("Foo"))))
        .andExpect(status().isCreated())
        .andExpect(jsonPath("$.name", is("Foo")))
        .andExpect(jsonPath("$.number", notNullValue()));
    }
    ...
}