Pytest fails with `sqlalchemy.exc.UnboundExecutionError: This session is not bound to a single Engine or Connection, and no context was provided to locate a binding.`#348

I just installed sqlalchemy-continuum to track changes to a few tables in a flask app. I was able to get the package up and running, but now my tests are failing when pytest fixtures are invoked. For what it's worth, the `db.session` binds to several databases, which is well supported by flask-sqlalchemy. I'm using Python 3.11.1. Here are the subset of package versions which could be relevant: ``` alembic==1.12.1 ; python_version >= '3.7' flask==2.3.3 flask-login==0.6.3 flask-migrate==3.1.0 flask-sqlalchemy==3.0.5 pytest==7.4.3 sqlalchemy==1.4.50 sqlalchemy-continuum==1.4.0 sqlalchemy-utils==0.41.1 ; python_version >= '3.6' werkzeug==3.0.1 ; python_version >= '3.8' ``` This is the abridged stack trace: ``` > pytest -x tests/test_api.py ..E _________________________________________ ERROR at setup of test_post_api _________________________________________ @pytest.fixture def group(): """Default test group.""" group = Group(name="test_group") db.session.add(group) > db.session.commit() tests/support/default_groups.py:27: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:1454: in commit self._transaction.commit(_to_root=self.future) .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:832: in commit self._prepare_impl() .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:811: in _prepare_impl self.session.flush() .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:3449: in flush self._flush(objects) .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:3478: in _flush self.dispatch.before_flush(self, flush_context, objects) .venv/lib/python3.11/site-packages/sqlalchemy/event/attr.py:247: in __call__ fn(*args, **kw) .venv/lib/python3.11/site-packages/sqlalchemy_continuum/manager.py:339: in before_flush uow = self.unit_of_work(session) .venv/lib/python3.11/site-packages/sqlalchemy_continuum/manager.py:301: in unit_of_work conn = session.connection() .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:1543: in connection bind = self.get_bind(**bind_arguments) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ self = <sqlalchemy.orm.session.Session object at 0x136f2c310>, mapper = None, clause = None, bind = None, _sa_skip_events = None, _sa_skip_for_implicit_returning = False def get_bind( self, mapper=None, clause=None, bind=None, _sa_skip_events=None, _sa_skip_for_implicit_returning=False, ): **Doc string redacted** # this function is documented as a subclassing hook, so we have # to call this method even if the return is simple if bind: return bind elif not self.__binds and self.bind: # simplest and most common case, we have a bind and no # per-mapper/table binds, we're done return self.bind # we don't have self.bind and either have self.__binds # or we don't have self.__binds (which is legacy). Look at the # mapper and the clause if mapper is clause is None: if self.bind: return self.bind else: > raise sa_exc.UnboundExecutionError( "This session is not bound to a single Engine or " "Connection, and no context was provided to locate " "a binding." ) E sqlalchemy.exc.UnboundExecutionError: This session is not bound to a single Engine or Connection, and no context was provided to locate a binding. .venv/lib/python3.11/site-packages/sqlalchemy/orm/session.py:2056: UnboundExecutionError ============================================================================================ short test summary info ============================================================================================= ERROR tests/test_api.py::test_post_api - sqlalchemy.exc.UnboundExecutionError: This session is not bound to a single Engine or Connection, and no context was provided to locate a binding. ``` I definitely need to support multiple database binds, so if anyone has any idea how to get around this issue it would be much appreciated! Thanks in advance.