Long origTargetSubscriptionCount = (Long) getEntityManager()
.createQuery("SELECT COUNT(*) FROM FeedSubscriber WHERE type = :type AND entityId = :entityId")
.setParameter("type", EntityType.GROUP).setParameter("entityId", entityId).getSingleResult();
// do the delete.
sut.execute(new DeleteAllFeedSubscriberByEntityTypeAndIdRequest(entityId, EntityType.GROUP));
getEntityManager().flush();
getEntityManager().clear();
// get new total number of subscriptions.