Unit testing repository spring org.springframework.beans.factory.UnsatisfiedDependencyException

Question

2. I'm using Spring Boot and MongoDB to create a simple school application. I want to test the methods that are defined in the service class but I get the following exception:

   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. My classes are the following:

4. Repository:

   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. Service:

   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. Unittest:

   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

This is happening due to the fact that you are using @ComponentScan in the wrong place.

Usually it is used in your Main Application class or in configuration classes not where you define the beans.

Please refer to this link: https://springframework.guru/spring-component-scan/

There is a similar question in here, and as you can see they are as well using @ComponentScan in the Main application

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