在我的Junit测试用例中，我尝试从Factory获取类的示例，但它总是返回null，APersistenceDAO和BPersistenceDAO类实现TestDao

@Component
public class TestDAOFactory {
 public TestDao(String type) {
     TestDaodao= null;
     System.out.println("dao type "+type);
     switch(type) {

     case "A":
         dao = new APersistenceDAO();
         break;
     case "B":
         dao= new BPersistenceDAO();
         break;

     }

    return dao;

 }

这是我的junit测试代码，用于获取Dao引用

@MockBean
  private TestDAOFactory daoFactory;
@Test
  void populateCacheFromPersistence() {

      TestDao dao = daoFactory.getDao("A");//always getting null
}

你能帮我检查一下我遗漏了什么吗？
我还添加了配置

@Configuration
public class TestConfiguration {

        @Bean
        @Primary
        public TestDAOFactory daoFactory() {
            return Mockito.mock(Test.class);
        }
}

从主测试类中，我尝试使用

@Autowired
  private TestDAOFactory daoFactory;