public MyEjbTest extends EJBTestCase<MyEjb> {

  public MyEjbTest() {
    super(MyEjb.class);
  }

  @Test
  public void testMyEjbMethodThatDoesJPAStuff() {
    // the same thing about transactions applies here as in the JPA-examples
    EntityManager em = getEntityManager();
    em.getTransaction().begin();

    // perhaps some entities needs to be in database for testing the method?
    SomeEntity entity = new SomeEntity();
    em.persist(entity);
    em.flush();
    em.clear();

    MyEjb instance = getBeanToTest();
    int returnValue = instance.orderSomethingForExample("productId", "someOtherParameter");
    assertTrue(1, returnValue);

    // make any database operations in the EJB flushed down to the database transaction
    em.flush();
    em.clear();

    // do some queries to check that the right stuff is in the database
    ...

    // don't forget to rollback changes to avoid affecting other tests
    em.getTransaction().rollback();
  }



  @Test
  public void testEjbMethodThatUsesCallerPrincipal() {
    // this method does not write to database, no need to work with the transaction

    Principal principal = new MyCustomPrincipal("EXAMPLE", "EXAMPLE");
    setCallerPrincipal(principal);

    MyEjb instance = getBeanToTest();
    String name = instance.getNameOfTheCallerPrincipal();
    assertEquals("EXAMPLE", name);

    // the caller principal will continue to be set so either reset it
    // by setting null or make sure each test for a method that uses it
    // will begin by calling setCallerPrincipal(...)
  }

  @Test
  public void testEjbMethodThatUsesOtherEjbs() {

    // use for example JMock to mock the EJBs your beanToTest depends on
    OtherEjbLocal otherEjb = someMockeryFramework.mock(OtherEjbLocal.class);

    ...
    set up expectations for the mocked ejb, depending on mockery framework
    ...

    // this can be done before or after you have aquired a reference to
    // the beanToTest
    injectEJB(OtherEJBLocal.class, otherEjb);

    MyEjb instance = getBeanToTest();

    instance.callTheMethod(someParameter);

    ...
    use mockery framework to verify behaviour
    ...


    // avoid having other tests call the mocked ejbs
    clearInjectedEJBs();
  }

  ...