单元测试库spring org.springframework.beans.factory.UnsatisfiedDependencyException

Question

2. 我正在使用Spring Boot和MongoDB来创建一个简单的学校应用程序。我想测试服务类中定义的方法，但我得到以下异常： org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name'com.backintime.BackInTimeSpring.Service.TeacherServiceTest': Unsatisfied dependency expressed through field 'teacherService'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.backintime.BackInTimeSpring.Service.TeacherService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
3. 我的课程如下：
4. 库：

   package com.backintime.BackInTimeSpring.Model.Repository;
   @Component
   @Repository
   public interface ITeacherRepository extends MongoRepository<Teacher,String> {
   
   @Query("{}")
   Stream<Teacher> findAllTeachers();
   
   List<Teacher> findByLastNameIgnoreCase(String lastName);
   List<Teacher> findByFirstNameIgnoreCase(String firstName);
   
   }

5. 服务：

   package com.backintime.BackInTimeSpring.Service;
   @Component
   @Service
   public class TeacherService {
   @Autowired
   private ITeacherRepository teacherRepository;
   
   public List<Teacher> retrieveAllTeachers(){
       return       this.teacherRepository.findAllTeachers().sorted(Comparator.comparing(Teacher::getLastName)).collect(Collectors.toList());
   }
   public Teacher retrieveTeachersById(String id) {
       return this.teacherRepository.findAllTeachers().filter(t -> t.getId().equals(id)).findFirst().get();
   }
   public List<Teacher> retrieveTeachersByLastName(String lastName){
       return this.teacherRepository.findByLastNameIgnoreCase(lastName);
   }
   public List<Teacher> retrieveTeachersByFirstName(String firstName){
       return this.teacherRepository.findByFirstNameIgnoreCase(firstName);
   }
   public void saveTeacher(Teacher t){
       this.teacherRepository.save(t);
   }
   
   public String greet() {
       return "Hello World";
   }

   }
6. 单元测试：

   package com.backintime.BackInTimeSpring.Service;
   @RunWith(SpringRunner.class)
   @ComponentScan(basePackages = "com.backintime.BackInTimeSpring")
   public class TeacherServiceTest {
   
   @Autowired
   TeacherService teacherService;
   @Test
   public void retrieveAllTeachers() {
       assertEquals(3, teacherService.retrieveAllTeachers().size());
   }

Answer 1

这是因为您在错误的地方使用@ComponentScan。

通常它在您的Main Application类或配置类中使用，而不是在您定义bean的位置。

请参考此链接：https://springframework.guru/spring-component-scan/

这里有一个类似的问题，你可以看到它们在主应用程序中使用@ComponentScan也是如此

How to use @ComponentScan together with test-specific ContextConfigurations in SpringJunit4TestRunner?