spring 和 junit4 测试 class 中的私有方法

Question

I have two spring bean class ServiceA and ServiceB. ServiceA dependents ServiceB. Show the code:

@Service // spring IOC annotation
public class ServiceA {

   @Autowired
   private ServiceB sb;

   // other code
   
   private void aMethod() {
      // other code
      sb.bMethod();
      // other code
   }

}

I write the ServiceA`s unit class by Junit4, flowing code:

@SpringBootTest
@RunWith(SpringRunner.class)
public class ServiceATest {

   @Autowired
   private ServiceA sa;

   @Test
   public void aMethodTest() {
        Method method = ReflectionUtils.findMethod(ServiceA.class, "aMethod");
        method.setAccessible(true);
        ReflectionUtils.invokeMethod(method, sa);
   }
}

I run the ServiceATest, when I debug the ServiceATest#aMethodTest(), the object 'sa' is a CGLIB proxy object. But I debug the ServiceA#aMethod(), the 'sb' is null.

I am confused. The object 'sa' is from Spring Bean Container, so it must be a complete object with Spring-DI. Why it`s field is null when i call sa.aMethod() method?

Answer 1

Not the answer you may be looking for, but private methods are supposed to be supporter methods and not need to be tested. Incase if you have written private method that needs unit test then PowerMock or PowerMockito will provide much better tests than java reflection.