Unit Testing with a Persistence Context

[Ashley Bye]

I'm struggling to find anything that will help explain how to unit test when I have an EntityManager (EM) injected into my bean using the @PersistenceContext annotation. I found this great article, but as far as I can tell I can't inject a mock EM. If it is possible to do so, please can someone explain how or point me to some references? Alternatively, is there any way to mock a PU and database access so I am not accessing a database for every test?

Edit: I am using JUnit and Mockito.
Edit: Actually added the link to the article!

[Janeice DelVecchio]

I imagine you're declaring your EM something like this:

    @PersistenceContext protected EntityManager entityManager;

Why not just create a package private setter for the field?

void setEM(EntityManager em){

this.entityManager = em;
}

Now the framework gives you an EM at runtime. But at test time, you can inject your mock.

[Janeice DelVecchio]

Alternatively, is there any way to mock a PU and database access so I am not accessing a database for every test?

Unit tests should not access the database. But you should try your hand at integration tests.

Most classes you write should implement an interface in order to be able to test one class at a time during unit testing.

[Ashley Bye]

Yes. I am more than a little stuck, and whilst I'm happy to just ignore any kind of testing whilst trying to learn some of the EE technologies, it's something I really need to get to grips with. I'm making a small little app where a user can register, login and keep track of the costs involved in buying, selling and moving from an old to a new house. I want to test that I can create a user, here's what I have so far:

User.java

package com.basicdesigns.houseapp.entities;

imports

@Entity
@Table(name = "member")
@NamedQueries(
{
    @NamedQuery(name = "User.findAll", query = "SELECT u FROM User u"),
    @NamedQuery(name = "User.findByEmail", query = "SELECT u FROM User u WHERE u.email = :email")
})
public class User implements Serializable
{
    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "member_id")
    private Integer userId;
    @Pattern(regexp="[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", message="Invalid email")
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 150)
    @Column(name = "email")
    private String email;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 300)
    @Column(name = "password")
    private String password;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 45)
    @Column(name = "firstname")
    private String firstname;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 45)
    @Column(name = "lastname")
    private String lastname;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "user")
    private List<Transaction> transactions;

    public User()
    {
        this.transactions = new ArrayList<>();
    }

    public Integer getId()
    {
        return userId;
    }

    public String getEmail()
    {
        return email;
    }

    public void setEmail(String email)
    {
        this.email = email;
    }

    public String getPassword()
    {
        return password;
    }

    public void setPassword(String password)
    {
        this.password = password;
    }

    public String getFirstname()
    {
        return firstname;
    }

    public void setFirstname(String firstname)
    {
        this.firstname = firstname;
    }

    public String getLastname()
    {
        return lastname;
    }

    public void setLastname(String lastname)
    {
        this.lastname = lastname;
    }

    public List<Transaction> getTransactions()
    {
        return transactions;
    }

    public void setTransactions(List<Transaction> transactions)
    {
        this.transactions = transactions;
    }
}

UserBeanLocal.java

package com.basicdesigns.houseapp;

imports

@Local
public interface UserBeanLocal
{
    public User createUser(String email, String password, String firstname, String lastname);
    public User getUser(int userId);
    public User getUser(String email);
    public User updateUser(User user);
    public User deleteUser(int userId);
    public User deleteUser(User user);
}

UserBean.java

package com.basicdesigns.houseapp;

imports

@Stateless
public class UserBean implements UserBeanLocal
{
    @PersistenceContext(unitName = "HouseAppPU")
    private EntityManager entityManager;
    
    // setter for entityManager to enable injection of a mock
    void setEntityManager(EntityManager em)
    {
        this.entityManager = em;
    }

    @Override
    public User createUser(String email, String password, String firstname, String lastname)
    {
        User user = new User();
        user.setEmail(email);
        user.setPassword(password);
        user.setFirstname(firstname);
        user.setLastname(lastname);
        
        entityManager.persist(user);
        
        return user;
    }

    @Override
    public User getUser(int userId)
    {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public User getUser(String email)
    {
        TypedQuery<User> query = entityManager.createNamedQuery("User.findByEmail", User.class);
        query.setParameter("email", email);
        query.setMaxResults(1);
        
        User user = query.getSingleResult();
        
        return user;
    }

    @Override
    public User updateUser(User user)
    {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public User deleteUser(int userId)
    {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }

    @Override
    public User deleteUser(User user)
    {
        throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.
    }
}

UserBeanTest.java

package com.basicdesigns.houseapp;

imports

public class UserBeanTest
{
    UserBean userBean = lookupUserBeanBean();
    @InjectMocks
    EntityManager entityManager;
    
    public UserBeanTest()
    {
    }
    
    @BeforeClass
    public static void setUpClass()
    {
    }
    
    @AfterClass
    public static void tearDownClass()
    {
    }
    
    @Before
    public void setUp()
    {
        userBean.setEntityManager(entityManager);
    }
    
    @After
    public void tearDown()
    {
    }

    @Test
    public void testCreateUser()
    {
        User user = userBean.createUser("[e-mail]", "pass", "Ashley", "Bye");
        
    }

    private UserBean lookupUserBeanBean()
    {
        try
        {
            Context c = new InitialContext();
            return (UserBean) c.lookup("java:global/com.basicdesigns_HouseApp_ejb_0.1-SNAPSHOT/UserBean!com.basicdesigns.houseapp.UserBean");
        } catch (NamingException ne)
        {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", ne);
            throw new RuntimeException(ne);
        }
    } 
}

Whilst I have some code in 2 of the methods and I know they work because I used a singleton bean to test them, it's not really in the spirit of unit testing or TDD. As mentioned right at the top, I'm a little perplexed as to how to continue. Any chance of a leg up?

[Janeice DelVecchio]

Ashley Bye wrote:Whilst I have some code in 2 of the methods and I know they work because I used a singleton bean to test them, it's not really in the spirit of unit testing or TDD. As mentioned right at the top, I'm a little perplexed as to how to continue. Any chance of a leg up?

I don't understand why you need a singleton bean.

    @Override
    public User createUser(String email, String password, String firstname, String lastname)
    {
        User user = new User();
        user.setEmail(email);
        user.setPassword(password);
        user.setFirstname(firstname);
        user.setLastname(lastname);
         
        entityManager.persist(user);
         
        return user;
    }

To unit test this mock, I'd....

@Test
public void createUser(){

// create the entity manager mock
// create the expectation that the mock will have the persist method called with a User object equal to the expected user
// set the EM mock on the Bean
// run the method
// run validate on the mock (some mock frameworks do this for you)

}

Now I don't use/know Mockito. I use JMock. I could help you with syntax if you aren't tied to mockito.

[Ashley Bye]

Janeice DelVecchio wrote:I don't understand why you need a singleton bean.

Nope, I don't either. I probably meant to go for stateless and just wasnt paying attention to what I wrote!

Janeice DelVecchio wrote:I use JMock. I could help you with syntax if you aren't tied to mockito.

I'll have a think about that one but appreciate the offer of help. Having just had a look through the syntax for JMock I find that of mockito easier to read. However, since I haven't really done any unit testing before and am at a omplete loss as to where / how to start (other than knowing I should test each unit) it might not make that much difference. Can I get back to you on the one? I suspect what I will do is finish this project so I know how the various elemnts interact, then tackle it again with tests to see just how different the final outcome is; plus I'll have a better idea of what I'm doing programming-wise and what I can and can't do with the various elements!