Pass object with added properties in Junit Mockito - junit

Question

I'm trying to do the Mockito for a method called generateToken() by using MockitoJUnitRunner.class. The source which I have tried to do as follows.
#RunWith(MockitoJUnitRunner.class)
public class LoginServiceTest {
#Mock
private UserRepository userRepository;
#Mock
private JwtTokenGenerator jwtTokenGenerator;
#InjectMocks
private LoginServiceImpl loginServiceImpl = new LoginServiceImpl();
private JwtUserDto user;
private String jwtSecret;
private String username;
private String password;
/**
* Initialize test data before test cases execution
*/
#Before
public void init() {
user = new JwtUserDto();
user.setId(1L);
user.setUsername("kray1");
user.setRole("Admin");
}
#Test
public void testLogin() {
try {
Mockito.when(jwtTokenGenerator.generateToken(user, jwtSecret)).thenReturn("myToken");
String actual = loginServiceImpl.login(username, password);
assertNotNull(actual);
} catch (Exception e) {
e.printStackTrace();
}
}
For that generateToken() method, I have to pass user object and a string. I'm declaring the user object in Init() method. When I try to execute this, the value return from the login method is null. But when I try to pass the user object as null then it will work as expected. So the problem should be with the user object.
Is there anything, like Mockito is blocking this kind of object with added properties or related thing? Please help to find a way to pass this user object with Mockito.
The LoginServiceImpl class as follows.
public class LoginServiceImpl implements LoginInterface {
#Autowired
private UserRepository userRepository;
#Autowired
private JwtTokenGenerator jwtTokenGenerator;
/*
* (non-Javadoc)
*/
public String login(String userName, String password) {
if (userName != null && password != null && !userName.isEmpty() && !password.isEmpty()) {
List<UserAuthenticationInfo> authInfo = userRepository.findUserRolesByUsernamePassword(userName, password);
if (authInfo != null && !authInfo.isEmpty()) {
JwtUserDto user = new JwtUserDto();
user.setId((long) authInfo.get(0).getUserId());
user.setUsername(userName);
user.setRole(authInfo.get(0).getUserRole());
return jwtTokenGenerator.generateToken(user, jwtSecret);
}
}
return null;
}
}

Answer 1

Do you have equals/hashcode on User class?
What is the result if you setup mock using
Mockito.when(jwtTokenGenerator.generateToken(any(User.class),any(String.class))
.thenReturn("myToken");
explanation:
When setting expectation as
Mockito.when(jwtTokenGenerator.generateToken(user, jwtSecret)).then...
You instruct your mock to act only for given user object. equals method is used for that. So, if your User is missing equals method, then reference equality is used. Two User objects (each crated with separate new User() call will not be equal.
For non-matching parameters in Mockito.when your mock (thenReturn) is not applied. Default value (null) is returned from mock.
Therefore I prefer to setup mocks not for specific arguments and then use Mockito.verify to check if expected interactions with mock took place. That way your tests are more expressive. Actually most of my object have equals/hashode not because of business reasons (I do not put them in collections) but only for testing and comparing using assertEquals.
Side note:
do not catch (Exception e) { e.printStackTrace(); } in test. It is much easier just to declare test method to throw Exception. End result is same (stacktrace printed) but with less code.

Answer 2

You are probably creating a new JwtUserDto() in your production code or getting the user instance from another mock. If you haven't overwritten the equals() method in your JwtUserDto class your 'test' user won't equal the 'production' user.
Make sure that the production and test user are the same instance or that they .equals each other.