Unit Test - Null mocked component is injected

Rzv Razvan :

I have the following use case:

I have a Test class with 3 components, from which 2 of them are inject into the third; I am using JUnit and Mockito for testing

public class MyTestClass{

 @Mock
 SomeService someService;

 @Mock 
 AnotherService anotherService;

 @InjectMock
 MainService mainService;

 @BeforeMethod
 public void init() {
   initMocks(this);
 }

 @Test
 public void test(){
  when(someService.someMethod(any())).thenReturn(something);
  when(anotherService.someMethod(any()).thenReturn(something);
  mainService.someMainMerhod();
  // ...other assert logic
 }
}

And here I have the MainService Spring component which has injected the two other components

 @Component
 public class MainService{
  @Autowired
  private SomeService someService; //Why here I have null component

  private AnotherService anotherService; // and here I have an initialized component ???

  public MainService(AnotherService anotherService){
    this.anotherService = anotherService;
  }

 // implementation
}

Question 1 : Why someService instance is null when I am using both constructor and @Autowired?

Question 2 : Why if I am using only the constructor without @Autowired and vice versa, everything works, since I do not load the Spring context... I have unit tests...

Datta2811 :

The Javadoc states: "Mockito will try to inject mocks only either by constructor injection, setter injection, or property injection in order. If any of the strategy fail, then Mockito won’t report failure; i.e. you will have to provide dependencies yourself."

Hence it will fail silently.