当 mocking 为 QueryBuilder 时出现 NullPointerException

Question

Problem:

I'm trying to create a test, using Mockito. This test Mocks a QueryBuilder and try to verify if everything is ok. But I am getting "java.lang.NullPointerException" . It seems like something hasn't been initialized, but i can't see what it is.

Code:

@RunWith(MockitoJUnitRunner.StrictStubs.class)
public class AcademicJPADAOTest {

    @Mock
    private EntityManager entityManager;
    @Mock
    private CriteriaBuilder cb;
    @Mock
    private CriteriaQuery<Academic> cq;
    @Mock
    private Root<Academic> root;

    @InjectMocks
    AcademicJPADAO academicjpadao;

    private String passwdcode = "83997689-22b6-4a7e-a801";


    @Test
    public void retrieveByPasswordCodeTest() throws PersistentObjectNotFoundException, MultiplePersistentObjectsFoundException {

        Academic academic = new Academic();

        when(entityManager.getCriteriaBuilder()).thenReturn(cb);
        when(cb.createQuery(Academic.class)).thenReturn(cq);
        when(cq.from(Academic.class)).thenReturn(root);
        when(cq.where(cb.equal(root.get(Academic_.passwordCode), passwdcode))).thenReturn(cq);

        when(academicjpadao.getEntityManager().createQuery(cq).getSingleResult()).thenReturn(academic);

        academicjpadao.retrieveByPasswordCode(passwdcode);

        verify(entityManager, times(1)).getCriteriaBuilder();

    }
}

Line error:

when(academicjpadao.getEntityManager().createQuery(cq).getSingleResult()).thenReturn(academic);

Answer 1

Maybe your academicjpadao isn't injected correctly in this part:

 @InjectMocks
 AcademicJPADAO academicjpadao;

so Use MockitoAnnotations.initMocks to initiate the @Mock and @InjectMocks objects.so you have to add to your class this method:

@Before
public void setup() {
    MockitoAnnotations.initMocks(this);
}