EJB3 unit testing - part one - dependency injection

You might want to use an embeddable container for this - but why really - cause it's really simple. EJB3 session beans are POJO's and should be tested like POJO's.

However there are some issues in order to get EJB3 unit tests working. One of them are dependency injection.

How does dependency injection work? Take a look at this method using reflection:

/**
* @param targetBean - the bean to inject into
* @param annotationClass - the annotation class representing the injection
* @param objectToInject - the object to inject into targetBean
*/

private void inject(Object targetBean, Class annotationClass, Object objectToInject)
{
 // Scan all (private and public fields) of the bean class
 for(Field fld : targetBean.getClass().getDeclaredFields())
 {
     // See if the specified annotation is present for the field
     if(fld.isAnnotationPresent(annotationClass))
     {
                // See if the field type is appropriate according to the object that is to be injected
  if(fld.getType().isAssignableFrom(objectToInject.getClass()))
  {
                    // Make sure that we can set the value of the field (e.g. if it's private)
      fld.setAccessible(true);
      try {
                        // Now set the field with the object to inject
   fld.set(targetBean, objectToInject);
   Logger.getLogger(getClass().getName()).info("Injected "+objectToInject.getClass().getName()+" into "+targetBean.getClass().getName());
      } catch (IllegalArgumentException ex) {
   Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
      } catch (IllegalAccessException ex) {
   Logger.getLogger(getClass().getName()).log(Level.SEVERE, null, ex);
      }
  }
     }
 }
}

Now let's see how we can inject the entitymanager and invoke a stateless ejb3 session bean:

// Create session bean instance
MySessionBean mySessionBean = new MySessionBean();
// Inject new entity manager
inject(mySessionBean,PersistenceContext.class,Persistence.createEntityManagerFactory("myTestPU").createEntityManager());
// Invoke session bean method
mySessionBean.hello();