Mockito / Junit5 org.opentest4j.AssertionFailedError for getter()

Question

If I make a JUnit Mockito test in the following method, it fails with org.opentest4j.AssertionFailedError: expected: not null. But the Mockito-(Parameter-)Test before with verify() and Assertions.assertNotNull() is ok. What am I doing wrong or what I don't understand? Here's my code:

JUnit5/mock-Test:

@Mock
private MyentityAServiceImpl myentityAServiceImplmock;
@Captor
private ArgumentCaptor<MyentityA> myentityAArgument;
@Mock
private MyentityBdao myentityBdaomock;
@Mock
private MyentityB myentityBmock;
@Mock
private Logger loggermock;
@InjectMocks
private MyentityBServiceImpl teServiceImpl;

@Test
public void setMyentityAOfTeIfNullByLanr17() {
    myentityBmock.setLanr7( "1234567" );
    final MyentityA myentityA = new MyentityA();
    mockito.when( myentityAServiceImplmock.findMyentityAByLanr17( myentityBmock.getLanr7() ) ).thenReturn( myentityA );
    mockito.when( myentityBdaomock.save( myentityBmock ) ).thenReturn( myentityBmock );
    myentityBmock = teServiceImpl.setMyentityAOfTeIfNullByLanr17( myentityBmock );
    mockito.verify( myentityBmock ).setMyentityA( myentityAArgument.capture() );
    Assertions.assertNotNull( myentityAArgument );
    Assertions.assertNotNull( myentityBmock.getMyentityA() );  // --> org.opentest4j.AssertionFailedError: expected: not <null>
}

Method to test:

  public MyentityB setMyentityAOfTeIfNullByLanr17( final MyentityB entity ) {
    MyentityA myentityA = entity.getMyentityA();
    if ( myentityA != null ) {
        return entity;
    }
    final String lanr17 = entity.getLanr7();
    myentityA = myentityAServiceImpl.findMyentityAByLanr17( lanr17 );
    if ( myentityA != null ) {
        entity.setMyentityA( myentityA );
        entity.setModuser( "root" );
        return myentityBdao.save( entity );
    }
    return entity;
}

Solution

Sorry your testing code is really too complex.
It describes too finely the flow of invocations of the objects manipulated in the method under test.
Besides you mock many things : dependencies, parameters of the method under tests.
At last you assign to the variable referencing the mocked parameter the return of the method under test. It makes things really unclear.

A test has to be straight understandable and that is not.
It took me about 5 mn to understand the error cause. It is a lot for such a simple code.

This assertion failure :

Assertions.assertNotNull( myentityBmock.getMyentityA() );  // --> org.opentest4j.AssertionFailedError: expected: not <null>

is due to the fact that in the tested method getMynEntityA() can only be null as myentityBmock is a mock and setting a field as you do here will have no effect on the real field and the associated getter behavior :

if ( myentityA != null ) {
    entity.setMyentityA( myentityA ); // here you invoke a mocked method.
    entity.setModuser( "root" );
    return myentityBdao.save( entity );
}

In fact with your way of testing that mainly describes the invocation flow of the tested method, that is enough :

mockito.verify( myentityBmock ).setMyentityA( myentityAArgument.capture() );

as you cannot test the side effect of setMyentityA().

But really I strongly advise you to unit test your method without mocking the parameter of the tested method.
It could look like :

@Test
public void setMyentityAOfTeIfNullByLanr17() {
    MyentityB entityB = new MyentityB(...) ;
    entityB.setLanr7( "1234567" );
    final MyentityA myentityA = new MyentityA();
    mockito.when( myentityAServiceImplmock.findMyentityAByLanr17( entityB.getLanr7() ) ).thenReturn( myentityA );
    mockito.when( myentityBdaomock.save(entityB) ).thenReturn(entityB);

    // action
    MyentityB entityActualB = teServiceImpl.setMyentityAOfTeIfNullByLanr17(entityB);

    // Perform content/logic assertion and no flow assertion :
    Assertions.assertEquals(myEntityA, entityActualB.getMyEntityA());
    Assertions.assertEquals("root", entityActualB.getModuser());
}

No tested code at all but it should help you to understand my intention.

Comments

[Horst Rothenholzer]

It works now. As you said, too many things were mixed and mocked which make it too complicated. I understand my error now - thanks!

[davidxxx]

You are welcome. Glad that you grasped the overall idea.

[GhostCat]

I see what you mean ;-)