我在测试类中遇到问题。
在我的类ParkingSpotService中有一个通过UUID的方法findByid，我想为此编写一个测试：

@Transactional
public Optional<ParkingSpotModel> findById(UUID id) {
    return parkingSpotRepository.findById(id);
}

我做了什么？我创建了一个测试类ParkingSpotServiceTest：

@SpringBootTest                                                                    
public class ParkingSpotServiceTest {

private static final UUID ID = UUID.fromString("35361d85-107c-4f1f-a047-263093161c1b");
private static final String PARKINGSPOTNUMBER = "1010";
private static final String LICENSEPLATECAR = "EAM3J81";
private static final String MODELCAR = "FIT";
private static final String BRANDCAR = "HONDA";
private static final String COLORCAR = "GREEN";
private static final LocalDateTime REGISTRATIONDATE = LocalDateTime.now();          
private static final String RESPONSIBLENAME = "Edison Azevedo";     
private static final String APARTMENT = "51";
private static final String BLOCK = "A";            

@InjectMocks
private ParkingSpotService service;

@Mock
private ParkingSpotRepository repository;

private ParkingSpotModel parkingSpot;   
private Optional<ParkingSpotModel> optionalParkingSpot;
Pageable pageable;

@BeforeEach
void setUp() {
    MockitoAnnotations.openMocks(this);
    startParkingSpot();
}

private void startParkingSpot() {
    parkingSpot = new ParkingSpotModel(ID, 
                                       PARKINGSPOTNUMBER, 
                                       LICENSEPLATECAR, 
                                       BRANDCAR, 
                                       MODELCAR, 
                                       COLORCAR, 
                                       REGISTRATIONDATE, 
                                       RESPONSIBLENAME, 
                                       APARTMENT, 
                                       BLOCK);      

    optionalParkingSpot = Optional.of(new ParkingSpotModel(ID, 
                                                           PARKINGSPOTNUMBER, 
                                                           LICENSEPLATECAR, 
                                                           BRANDCAR, 
                                                           MODELCAR, 
                                                           COLORCAR, 
                                                           REGISTRATIONDATE, 
                                                           RESPONSIBLENAME, 
                                                           APARTMENT, 
                                                           BLOCK));                 
}

}
在我创建了一个测试之后

@Test
void whenFindParkingSpotByIDThenReturnAnParkingSpotInstance() {     
    Mockito.when(repository.findById(Mockito.any(UUID.class))).thenReturn(optionalParkingSpot); 
    Optional<ParkingSpotModel> response = service.findById(ID); 
  **//above my response is value = null  ->  Optional.empty.    Why????????**
    Assertions.assertNotNull(response);     

    Assertions.assertEquals(java.util.Optional.class, response.getClass());             

    Assertions.assertEquals(ID, response.get().getId());
    //here my test broke because my response "java.util.NoSuchElementException: No value present"

观察结果：
1.当我检查optionalParkingSpot时，所有数据都在那里。Mockito.when(repository.findById(Mockito.any(UUID.class))).thenReturn(optionalParkingSpot);
1.检查ID时，正确显示UUID（35361 d85 - 107 c-4f 1f-a047 - 263093161 c1 b）Optional<ParkingSpotModel> response = service.findById(ID);
我的“响应”有什么问题？为什么数据是value = null -〉Optional. empty.？？？