class SomeTest(ORMTest):

    def define_tables(self, metadata):
        Table('users', metadata, ...)
        Table('addresses', metadata, ...)

    def define_classes(self):
        class User(TestEntity):
            pass
        class Address(TestEntity):
            pass

    def test_1(self):
        User, users = self.lookup()

        mapper(User, users)
        # ...

    def test_2(self):
        Address, addresses, User = self.lookup()

        mapper(Address, addresses, properties={
                'user': relation(User)
                })
        # ...