Spring Boot Test: UserControllerTest Fails When Using Jackson ObjectMapper To Convert Model To JSON String

Question

I'm testing a @RestContoller in Spring Boot which has a @PostMapping method and the method @RequestBody is validated using @Valid annotation. To test it, I'm using MockMvc and in order to populate request body content I'm using Jackson ObjectMapper; however, when the model is passed, the test fails:

MockHttpServletRequest:
      HTTP Method = POST
      Request URI = /api/user/register
       Parameters = {}
          Headers = [Content-Type:"application/json"]
             Body = <no character encoding set>
    Session Attrs = {}

Handler:
             Type = com.springboottutorial.todoapp.controller.UserController
           Method = public org.springframework.http.ResponseEntity<java.lang.String> com.springboottutorial.todoapp.controller.UserController.register(com.springboottutorial.todoapp.dao.model.User)

Async:
    Async started = false
     Async result = null

Resolved Exception:
             Type = org.springframework.http.converter.HttpMessageNotReadableException

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

FlashMap:
       Attributes = null

MockHttpServletResponse:
           Status = 400
    Error message = null
          Headers = []
     Content type = null
             Body = 
    Forwarded URL = null
   Redirected URL = null
          Cookies = []

java.lang.AssertionError: Status 
Expected :200
Actual   :400

User Model:

@Entity
@Table(name = "users",
        uniqueConstraints = @UniqueConstraint(columnNames = {"EMAIL"}))
public class User {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "ID")
private long id;

@Column(name = "FIRST_NAME")
@NotNull
private String firstName;

@Column(name = "LAST_NAME")
@NotNull
private String lastName;

@Column(name = "EMAIL")
@NotNull
@Email
private String emailAddress;

@Column(name = "PASSWORD")
@NotNull
private String password;

@Column(name = "CREATED_AT")
@NotNull
@Convert(converter = LocalDateTimeConveter.class)
private LocalDateTime createdAt;

@Column(name = "UPDATED_AT")
@NotNull
@Convert(converter = LocalDateTimeConveter.class)
private LocalDateTime updatedAt;

public User(@NotNull String firstName, @NotNull String lastName,
                @NotNull @Email String emailAddress, @NotNull String password,
                @NotNull LocalDateTime createdAt, @NotNull LocalDateTime updatedAt) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.emailAddress = emailAddress;
        this.password = password;
        this.createdAt = createdAt;
        this.updatedAt = updatedAt;
    }

//setters and getters: omitted

UserController:

@RestController
@RequestMapping("/api/user")
public class UserController {

    @Autowired
    UserService userService;

    @PostMapping("/register")
    public ResponseEntity<String> register(@RequestBody @Valid User user){
        userService.createUser(user);
        return ResponseEntity.ok().build();
    }
}

UserControllerTest:

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc(addFilters = false)
public class UserControllerTest {

    @Autowired
    MockMvc mockMvc;

    @Test
    public void whenRequestValid_thenReturnStatusOk() throws Exception{
        User user = new User("John", "QPublic", "[email protected]",
                "123456789", LocalDateTime.now(), LocalDateTime.now());      
        mockMvc.perform(MockMvcRequestBuilders.post("/api/user/register")
                .content(new ObjectMapper().writeValueAsString(user))
                .contentType(MediaType.APPLICATION_JSON)
                )
                .andExpect(MockMvcResultMatchers.status().isOk());
    }
}

When I build JSON string manually, the test passes:

String json = "{\n" +
                "\t\"firstName\" : \"John\",\n" +
                "\t\"lastName\" : \"QPublic\",\n" +
                "\t\"password\" : \"123456789\",\n" +
                "\t\"createdAt\" : \"2016-11-09T11:44:44.797\",\n" +
                "\t\"updatedAt\" : \"2016-11-09T11:44:44.797\",\n" +
                "\t\"emailAddress\" : \"[email protected]\"\n" +
                "}";

        mockMvc.perform(MockMvcRequestBuilders.post("/api/user/register")
                .content(json)
                .contentType(MediaType.APPLICATION_JSON)
                )
                .andExpect(MockMvcResultMatchers.status().isOk());

Answer 1

As chrylis mentioned in comments, the problem occurred due to Java 8 Date & Time API and Jackson serialization conflicts. By default, ObjectMapper doesn't understand the LocalDateTime data type, so I need to add com.fasterxml.jackson.datatype:jackson-datatype-jsr310 dependency to my maven which is a datatype module to make Jackson recognize Java 8 Date & Time API data types. A stackoverflow question and a blog post helped me to figure out what actually my problem was.