// Create UserService mock
UserService service = mock(UserService.class);
when(service.login("user", "password")).thenReturn(Optional.of(user));
LoginRequest req = new LoginRequest();
req.setName("user");
req.setPassword("password");
UserREST userREST = new UserREST(null, null, null, service, null, null, null);
SessionHelper sessionHelper = mock(SessionHelper.class);
userREST.login(req, sessionHelper);