使用 mockito 测试 Hibernate DAO 方法

Question

I have visited a lot of blogs and websites to learn how I can test my DAO methods in Hibernate with Mockito, but I haven't found any specific example that could help me with my code. All I have found is that I have to use Integration test instead of JUnit test but I don't really know how to do that with my code.

QUESTION: How can I test my DAO methods as good as possible?

MY CODE:

My test with only the mockito part:

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;

@RunWith(MockitoJUnitRunner.class)
public class UserDAOTest
{

@Mock
private UserDAO userDAO;

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

@Test
public void testAddUser_AddsNewUser()
{

}

@Test
public void testDeleteUser_DeletesUser()
{

}


@Test
public void testGetUser_FetchUser()
{

}

@Test
public void testGetUsers_FetchesAllUsers()
{

}
}

My UserDAO:

import Hibernate.HibernateUtil;
import Hibernate.Models.User;
import org.hibernate.HibernateException;
import org.springframework.stereotype.Repository;
import org.hibernate.Session;
import org.hibernate.Transaction;
import java.util.List;

//@Transactional
@Repository
public class UserDAO extends GeneralDAO
{

public void addUser(User user)
{
    add(user);
}


/**
 * Deletes a user from the database based on the userID
 * @param userID
 */

public void deleteUser(int userID)
{
    User user = new User();
    delete(userID, user);
}


public User getUser(int userID) throws Exception
{
    Transaction transaction = null;
    User user = null;
    try (Session session = HibernateUtil.getSessionFactory().openSession()) 
{
        // start a transaction
        transaction = session.beginTransaction();

        // Gets the user object
        user = session.get(User.class, userID);

        // commit transaction
        transaction.commit();

        //closing session
        session.close();

        return user;

    } catch (Exception e) {
        if (transaction != null) {
            transaction.rollback();
        }
        e.printStackTrace();
        return user;
    }
}


public List<User> getUsers() throws HibernateException, Exception
{
    try(Session session = HibernateUtil.getSessionFactory().openSession()){
        return session.createQuery("FROM User", User.class).getResultList();
    }

}
}

My GeneralDAO:

import Hibernate.HibernateUtil;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.springframework.stereotype.Repository;

//@Transactional
@Repository
public class GeneralDAO
{
public void add(Object obj)
{
    Transaction transaction = null;
    try (Session session = HibernateUtil.getSessionFactory().openSession())
    {
        // start a transaction
        transaction = session.beginTransaction();

        // add the user object
        session.save(obj);

        // commit transaction
        transaction.commit();

        //closing session
        session.close();


    } catch (Exception e)
    {
        if (transaction != null)
        {
            transaction.rollback();
        }
        e.printStackTrace();
    }
}

public void delete(int userID, Object obj)
{
    Transaction transaction = null;
    try (Session session = HibernateUtil.getSessionFactory().openSession())
    {

        obj = session.load(obj.getClass(), userID);

        // start a transaction
        transaction = session.beginTransaction();

        //deleting the user from the db
        session.delete(obj);

        // commit transaction
        transaction.commit();

        //closing session
        session.close();


    } catch (Exception e)
    {
        if (transaction != null)
        {
            transaction.rollback();
        }
        e.printStackTrace();
    }
}
}

Answer 1

What you read about testing DAO is the correct way.
Don' test with Mockito the DAO/repository layer.

You don't want to write an unit test that asserts that a flow of statements was indeed invoked :

// start a transaction
transaction = session.beginTransaction();

// add the user object
session.save(obj);

// commit transaction
transaction.commit();

//closing session
session.close();

Writing this kind of test means writing mainly mock to describe the flow.
No value because it checks nothings in terms of logical/behavior.
Similarly, asserting a query is useless. You could write "SELECT SELECT SELECT" as query in your DAO and your test could still success if you rely on checking query text.

You use Spring. If you also use Spring Boot, you should rely on the @DataJpaTest test slicing that focuses on testing the data access components.
Otherwise, don't worry. We did it before Spring Boot. So we could still do it.
Configure an in memory database (H2 for example) for your test, and clear/populate data according to the tested method.
For example :

@Autowired
UserDAO userDAO;

@Test
public void getUser_retrieves_users_added_by_addUser(){
    User addedUser = userDAO.add(new User("foo", "bar"));
    // ... flush data in the database and clear first cache level to avoid cache using
    User expectedUser =  userDAO.get(addedUser.getId());
   // assert the expected User
}

@Before
public void tearDown(){
   // clear data in the database
}