findById 看不到模拟中的对象

问：

我正在为 UserServiceImpl 服务编写测试。

    public User getUserById(long id) {
        Optional<User> optional = userRepository.findById(id);
        User user = null;
        if (optional.isPresent()) {
            user = optional.get();
        } else {
            throw new RuntimeException("User not found for id: " + id);
        }
        return user;
    }

UserServiceImplTest

@ExtendWith(MockitoExtension.class)
public class UserServiceImplTest {

    @Mock
    private UserRepository userRepository;
    @InjectMocks
    private UserServiceImpl userService;

    @Test
    public void shouldReturnUserById() {
        List<User> users = getUsers();
        Long id = 1L;

        Mockito.when(userRepository.findAll()).thenReturn(users);

        System.out.println(users.get(0).getId());

        User result = userService.getUserById(id);

        Assertions.assertNotNull(result);
        Assertions.assertEquals(users.get(0), result);
    }

    private List<User> getUsers() {
        User firstUser = new User();
        User secondUser = new User();

        firstUser.setId(1L);
        firstUser.setName("Rob");
        firstUser.setLastName("King");
        firstUser.setDepartment("Supply");
        firstUser.setPosition("Team lead");

        secondUser.setId(2L);
        secondUser.setName("Mike");
        secondUser.setLastName("Wilson");
        secondUser.setDepartment("Sale");
        secondUser.setPosition("Specialist");

        return List.of(firstUser, secondUser);
    }
}

在 userService.getUserById（id） 方法中运行测试时 - java.lang.RuntimeException：找不到 id 的用户：1 尽管存储库中存在具有相同 ID 的对象。 请告诉我我错过了什么？