em.getTransaction().rollback();
assertThat( getNumberOfEntities( em ) ).isEqualTo( 1 );
em.getTransaction().begin();
poem = em.find( Poem.class, poem.getId() );
assertThat( poem ).isNotNull();
assertThat( poem.getName() ).isEqualTo( "L'albatros" );
em.remove( poem );
poem2 = em.find( Poem.class, poem2.getId() );
assertThat( poem2 ).isNull();