.py

class BaseTestCase(unittest.TestCase):
    def setUp(self):
        self.tx = postgresql.db.begin()
        postgresql.db = self.tx
        for store in postgresql.__dict__.values():
            for attempt in ['_PostgreSQLStore__db', '_db', 'db']:
                if hasattr(store, attempt):
                    setattr(store, attempt, self.tx)
                    break
        store._PostgreSQLStore__tl = threading.local()

    def tearDown(self):
        self.tx.__exit__(Exception, Exception(), None)