assertTrue(dao.retrieveAllWorldEntities().size() == 1);
assertTrue(dao.newWorldEntityOf(this.world2).isPresent());
assertTrue(dao.retrieveAllWorldEntities().size() == 2);
assertTrue(dao.findWorldEntityById(3).isPresent());
assertFalse(dao.newWorldEntityOf(this.world2).isPresent());
assertTrue(dao.findWorldEntityById(3).isPresent());
assertTrue(dao.retrieveAllWorldEntities().size() == 2);
assertTrue(dao.newWorldEntityOf(this.world3).isPresent());
assertTrue(dao.findWorldEntityById(5).isPresent());
assertFalse(dao.newWorldEntityOf(this.world3).isPresent());
assertTrue(dao.findWorldEntityById(5).isPresent());