Repository mocking doesn`t work. Return wrong Http status

Question

I have createUser() method in my UsserServiceImpl.java

public ResponseEntity<UserDto> createUser(UserDto userDto) {
        User user = new User(userDto.getName(), userDto.getProducts(), getCurrentDate(), null);
        user = repository.save(user);
        return user != null ? new ResponseEntity<>(convertToDto(user), HttpStatus.OK) : new ResponseEntity<>(HttpStatus.BAD_REQUEST);
}

I have a unit test for this method

@Mock
private UserRepository userRepository;

private UserService userService;

@BeforeEach
void init() {
    userService = new UserServiceImpl(userRepository);
}

@Test
void createUser() {
    Set<Product> productSet = createProducts();
    LocalDate date = getCurrentDate();
    User user = new User("Max", productSet, date, null);

    when(userRepository.save(user)).thenReturn(new User(UUID.fromString("e7485042-b46b-11e9-986a-b74e614de0b0"), "Max", productSet, date, null));

    ResponseEntity<UserDto> userDto = userService.createUser(new UserDto("Max", productSet));

    assertEquals(HttpStatus.OK, userDto.getStatusCode());
    assertEquals(userDto.getBody(), new UserDto("Max", productSet));
}

When I execute test I get an `\\error:

org.opentest4j.AssertionFailedError: Expected :200 OK Actual :400 BAD_REQUEST

as I understand, the problem is that repository.save() the method returns null.
I totally don`t understand why this string

when(userRepository.save(user))
 .thenReturn(
   new User(UUID.fromString("e7485042-b46b-11e9-986a-b74e614de0b0"), 
   "Max", 
   productSet, 
   date, 
   null)
 );

doesn`t work properly, any help is appreciated!

Answer 1

It is because there are 2 User objects being involved in this scenario. Inside createUser() at runtime, there is a new User object will be created. That User object is not equal to the User object you create when you write the Mock statement. Therefore, you can accept any arbitrary User object when you define the mock statement.

Mockito.any(User.class)

If you intend those 2 objects to be equal; User class should provide a proper equals() implementation. It seems it doesn't provide such a implementation. So, you can try something like below.

    when(userRepository.save(any(User.class)))
   .thenReturn(
      new User(UUID.fromString("e7485042-b46b-11e9-986a-b74e614de0b0"), 
              "Max", 
              productSet, 
              date, 
              null)
   );