public void testTrips() {
OpenJPAEntityManager pm = _factory.createEntityManager();
Extent ext = pm.createExtent(DataStoreTripsPC.class, true);
for (Iterator itr = ext.iterator(); itr.hasNext();)
itr.next();
ext.closeAll();
pm.close();
// there might be more than 1 trip if subclasses need to be
// initialized and so forth, but make sure there isn't more than
// 1 + # objects trips to the DB