After working with devs on both the OpenEJB and the OpenJPA teams, I think that for anything other than trivial persistence units and entity relations, it is probably necessary to manually find a list of all of the entities of a given type, iterate over that list, and use the entitymanager.remove() method to clean out the entities in the datastore between unit tests. Although this method is extremely slow and will be a big hit to productivity, I cannot get a succession of "DELETE FROM table" queries to reliably remove objects without crashing because of entity relations and foreign keys, and have not yet had the former method crash on me.
The "DELETE FROM table" mechanism seems to wreak havoc on the cascading rules and cause problems for itself when done in succession to multiple tables--I don't know enough about the guts of the query execution mechanism to say why, and that's alright. If we need to build an example application for either project to test this behavior at a later time, I'll be able to provide a sufficiently complex persistence unit to really stress test things. In the meantime, I really am itching to get back to actual development, so I'm going to revert and move forward using the other method for the time being. Thanks to Dain, Panaki, Jacek, Adam, and Patrick. Cheers, -- Alex
