BaseTestData.java

package blog.common;

import java.lang.reflect.*;
import javax.annotation.*;
import javax.persistence.*;

import static org.junit.Assert.*;

public abstract class BaseTestData<E extends BaseEntity>
{
   private final Class<E> entityClass;
   @PersistenceContext private EntityManager em;
   private int id;

   @SuppressWarnings("unchecked")
   protected BaseTestData()
   {
      entityClass = (Class<E>) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];
   }

   @PostConstruct
   private void beginTransaction()
   {
      EntityTransaction transaction = em.getTransaction();

      if (!transaction.isActive()) {
         transaction.begin();
      }
   }

   @PreDestroy
   private void endTransaction()
   {
      EntityTransaction transaction = em.getTransaction();

      if (transaction.isActive()) {
         transaction.rollback();
      }
   }

   protected final int getId() { return id++; }

   public final void save(BaseEntity entity)
   {
      if (entity.getId() == null) {
         em.persist(entity);
      }

      em.flush();
   }

   public final E find(Long entityId)
   {
      return em.find(entityClass, entityId);
   }

   public final void detachFromPersistenceContext(BaseEntity entity)
   {
      em.detach(entity);
   }

   public final E assertSavedToDB(E entity)
   {
      if (em.contains(entity)) {
         em.detach(entity);
      }

      E fromDb = em.find(entityClass, entity.getId());

      assertEquals(entity.getId(), fromDb.getId());
      assertNotSame(entity, fromDb);
      return fromDb;
   }

   public final void assertDeletedFromDB(BaseEntity entity)
   {
      BaseEntity deletedEntity = find(entity.getId());
      assertNull(deletedEntity);
   }

   public final E buildAndSave()
   {
      E entity = build();
      save(entity);
      return entity;
   }

   protected abstract E build();
}