Question

This is my java class:

public class Finder {
  @PersistenceContext(unitName = "abc")
  EntityManager em;
  public boolean exists(int i) {
    return (this.em.find(Employee.class, i) != null);
  }
}

This is the unit test:

public class FinderTest {
  @Test public void testSimple() {
    Finder f = new Finder();
    assert(f.exists(1) == true);
  }
}

Testing fails with NullPointerException since Finder.em is not injected by anyone. How should I handle this situation properly? Does there any best practice exist?

Answer 1

Without a container like Spring (or something like Unitils – which is Spring based), you will have to inject the entity manager manually. In that case, you could use something like this as base class:

public abstract class JpaBaseRolledBackTestCase {
    protected static EntityManagerFactory emf;

    protected EntityManager em;

    @BeforeClass
    public static void createEntityManagerFactory() {
        emf = Persistence.createEntityManagerFactory("PetstorePu");
    }

    @AfterClass
    public static void closeEntityManagerFactory() {
        emf.close();
    }

    @Before
    public void beginTransaction() {
        em = emf.createEntityManager();
        em.getTransaction().begin();
    }

    @After
    public void rollbackTransaction() {   
        if (em.getTransaction().isActive()) {
            em.getTransaction().rollback();
        }

        if (em.isOpen()) {
            em.close();
        }
    }
}