Mock objects returns null

Question

I have below Test class:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = SpringTestConfig.class)
public class UserServiceTest {

    @Inject
    private UserRepository userRepository;

    @Inject
    private UserService userService;

    @Test
    public void testProcessInvoice() throws SQLException {
        User user = new User();
        user.setFirstName("abc");
        when(userRepository.save(any(User.class))).thenReturn(user);
        Assert.assertNotNull(userService);
        User savedUser = userService.save(user);
        Assert.assertEquals("abc", savedUser.getFirstName());
    }
}

I have below SpringTestConfig.java

@Configuration
public class SpringTestConfig {
    @Bean
    public UserService userService() {
        return Mockito.mock(UserService.class);
    }
    @Bean
    public UserRepository userRepository() {
        return Mockito.mock(UserRepository.class);
    }
}

call to User savedUser = userService.save(user); returns null user object. I am not able to figure it out why it is returning null.

EDIT: UserRepository is JpaRepository, if this is a problem

public interface UserRepository extends JpaRepository<User, Long> {
}

nicholas.hauschild · Accepted Answer · 2015-08-27 15:33:56Z

3

Your UserService is a mock object, and has no defined behavior for dealing with the #save(User) method.

Mocking the object under test is probably not what you are after here. I would recommend your objects under test are instantiated in the test, and injected with the mocks or stubs of the objects that they utilize.

edited Aug 27, 2015 at 15:33

answered Aug 27, 2015 at 15:18

nicholas.hauschild

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2 Comments

Nitesh Virani Over a year ago

yes, correct so I had run again with when(userService.save(any(User.class))).thenReturn(user); and it returns the object. how does it test the functionality of userService.save since I have defined mocking behavior on that?

nicholas.hauschild Over a year ago

You aren't if you are mocking your object under test!

Nathan Hughes · Accepted Answer · 2015-08-27 15:22:32Z

2

Your configuration needs to return a real UserService:

@Configuration
public class SpringTestConfig {
    @Bean
    public UserService userService() {
        return new UserServiceImpl(); // or whatever your implementation is 
    }
    @Bean
    public UserRepository userRepository() {
        return Mockito.mock(UserRepository.class);
    }
}

Mocks are for collaborators, not for the thing you're testing.

answered Aug 27, 2015 at 15:22

Nathan Hughes

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1 Comment

Nitesh Virani Over a year ago

I have followed what you said, like return new UserServiceImpl(userRepository()); now userService.save(user) calls actual implementation. Thanks.

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