在测试类上调用方法时，模型映射程序获取空指针异常

Question

当我调用模型映射器实体到DTO转换器方法时，我总是得到空指针异常。

这是将dto转换为实体的转换器服务，反之亦然

我以前没有处理过DTO，这是我第一次使用DTO，我还需要知道这是我实现DTO转换器服务的最佳方式吗，或者是否有任何建议。

@Autowired
private ModelMapper modelMapper;

@Bean
public ModelMapper modelMapper() {
    return new ModelMapper();
}

@Override
public NotificationDto entityToDtoNotification(Notification notification) {
    ModelMapper mapper = new ModelMapper();
    return mapper.map(notification, NotificationDto.class);
    
}

@Override
public Notification dtoToEntityNotification(NotificationDto notificationDto) {

    ModelMapper mapper = new ModelMapper();
    return mapper.map(notificationDto, Notification.class);

}

当我在测试调用中调用该方法时，我得到空值

class NotificationServiceImplTest {

    @Autowired
    private NotificationServiceImpl notificationService;

    @MockBean
    private NotificationRepository notificationRepository;

    @Autowired
    ConverterServiceImpl converterService;

    @Test
    public void testCreateTicket() {

        Notification notification = new Notification();
        notification.setId(1);
        notification.setMessage("Hello Hashan");


        NotificationDto notificationDto = new NotificationDto();

         
        //I get the null value as return

        notificationDto=converterService.entityToDtoNotification(notification);



        Mockito.when(notificationRepository.save(notification)).thenReturn(notification);
        
        assertThat(notificationService.save(notificationDto)).isEqualTo(notification);

        converterService.entityToDtoNotification(notification);
    }


}

通知实体

@Entity
@Table(name = "notification")
public class Notification {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    private String message;


    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public Notification() {
    }

    public Notification(int id, String message) {
        this.id = id;
        this.message = message;
    }
}

通知DTO

public class NotificationDto {

    private int id;
    private String message;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public NotificationDto(int id, String message) {
        this.id = id;
        this.message = message;
    }

    public NotificationDto() {
    }
}

Answer 1

解决方案：在测试类上添加@SpringBootTest注释后，我可以从转换器服务访问值，而不会出现空指针异常

@SpringBootTest
class NotificationServiceImplTest {

Answer 2

您应该使用@RunWith（SpringRunner.class）注释您的测试，以便您可以使用spring上下文自动关联属性。

请参阅：https://docs.spring.io/spring-boot/docs/1.5.2.RELEASE/reference/html/boot-features-testing.html