[FIXED] Problems with mockito. Unit test

Issue

I'm unit testing with mockito and I get nulls in the repository, after doing a .save().

My test:

....
    @BeforeEach
    void setUp() {
        // USUARIO
        user = new User();
        user.setUserName("Username A");
        user.setPassword("Pass A");
        user.setConfirmPassword("Pass A");
    }


    @MockitoSettings(strictness = Strictness.LENIENT)
    @Test
    void createUserNoExistValidConfirmation() throws Exception {
        User userToPassParam = new User();
        userToPassParam.setUserName("Username_Aa");
        userToPassParam.setPassword("Pass A");
        userToPassParam.setConfirmPassword("Pass A");
        // checkUserNameAvailable
        Mockito.when(userDaoRepository.findByUserName(userToPassParam.getUserName())).thenReturn(Optional.ofNullable(user));
        // -- checkPasswordValid
        Mockito.when(bCryptPasswordEncoder.encode(userToPassParam.getPassword())).thenReturn(user.getPassword());
        // -- save
        Mockito.when(userDaoRepository.save(userToPassParam)).thenReturn(user);

        User userToCallServiceImpl = new User();
        userToCallServiceImpl.setUserName("Username A");
        userToCallServiceImpl.setPassword("Pass A");
        userToCallServiceImpl.setConfirmPassword("Pass A");
        User user = userServiceImpl.createUser(userToCallServiceImpl); // HERE GET NULLS

        System.out.println("User: " + user);
        System.out.println("this.user: " + this.user);
        Assertions.assertEquals(user.getUserName(), this.user.getUserName());
    }
.....

value of userToPassParam passed parameter: the expected object

I only treat 3 values of the object, "userName, password, confirmPassword" the other values do not matter to me.

When I try to pass the test: userServiceImpl

@Override
public User createUser(User user) throws Exception {
    if (checkUserNameAvailable(user) && checkPasswordValid(user)) {
        // cogemos el estado de la DB para más adelante: user = save()
        String encodePassword = bCryptPasswordEncoder.encode(user.getPassword());
        user.setPassword(encodePassword);
        user = userDaoRepository.save(user);
    }
    return user;
}

The user has a "before save" value. Right when it saves I get a null.

After repository.save(object) the object returned by the .save "mock object" is null.

I don't understand very well why the .save returns null, when in the "when" I specify what to return. It's as if mockito didn't intercept the .save() to return the object.

Note: I use Junit 5, Mockito 4.6.1

I am expecting the .save() to return the "user" as I specified in my @BeforeEach void setUp() {...}. Mockito.when(userDaoRepository.save(userToPassParam)).thenReturn(user); That is, the intercept of the .save() so that it returns the object.

Solution

I have fixed this with an ArgumentMatchers. For some unknown reason, Mockito needs it.

import static org.mockito.ArgumentMatchers.any;

Mockito.when(userDaoRepository.save(any(User.class))).thenReturn(user);

Information source: here

Note: I have also implemented equals and hashCode overrides, but it doesn't detect them.

Answered By - Naslo Flaquez
Answer Checked By - Robin (JavaFixing Admin)