code: /** 
   * Rollback test
   */
  @Test public void testSafeRollback(){
    String testClusterName="don't save";
    EntityManager entityManager=injector.getInstance(OrmTestHelper.class).getEntityManager();
    entityManager.getTransaction().begin();
    ClusterEntity clusterEntity=new ClusterEntity();
    clusterEntity.setClusterName(testClusterName);
    entityManager.persist(clusterEntity);
    entityManager.getTransaction().rollback();
    assertNull("transaction was not rolled back",injector.getInstance(ClusterDAO.class).findByName(testClusterName));
  }
  