### Question:
AadUserService implements UserService { @Override public Collection<User> findAll() { return Lists.newArrayList(this.aadUserRepository.findAll()); } @Autowired  AadUserService(
      AadUserRepository aadUserRepository, AadUserListUpdater aadUserListUpdater); @Override Collection<User> findAll(); @Override User getCurrentUser(); @Override User findById(UUID userId); @Override boolean doesUserExist(UUID userId); @EventListener(ApplicationReadyEvent.class) void updateUsersAtStartup();  }### Answer:
@Test public void test_expectEmptyUserList() { when(aadUserRepository.findAll()).thenReturn(new ArrayList<>()); Assert.assertTrue(aadUserService.findAll().isEmpty()); }
@Test public void test_expectUserListWithTwoEntities() { Collection<AadUser> users = Arrays.asList(new AadUser(), new AadUser()); when(aadUserRepository.findAll()).thenReturn(users); Assert.assertEquals(2, aadUserService.findAll().size()); }