Disable session.remove on flask_sqlalchemy.SQLAlchemy

[janbuchar]

With Flask-SQLAlchemy 2.4.0, SQLAlchemy 1.3.3 and pytest-flask-sqlalchemy 1.0.2, I sometimes (non-deterministically) got DetachedInstanceError because the session instantiated in the flask_sqlalchemy.SQLAlchemy extension already terminated the session (https://github.com/pallets/flask-sqlalchemy/blob/master/flask_sqlalchemy/__init__.py#L849).

Adding something like this to conftest.py helped.

mocker.patch.object(sqla.session, "remove", lambda: None)

[jeancochrane]

Sorry it took me so long to get to this @Teyras! That seems like a pretty nasty race condition. I'd welcome a PR making this change if you've had some success with it. We'll have to be careful to preserve the remove() function somewhere, since we use it ourselves to tear down the session:

pytest-flask-sqlalchemy/pytest_flask_sqlalchemy/fixtures.py

Lines 75 to 78 in 7cb57c0

	@request.addfinalizer
	def teardown_transaction():
	# Delete the session
	session.remove()

But we should probably be able to get away with preserving the method the same way we do close(), commit(), and rollback():

pytest-flask-sqlalchemy/pytest_flask_sqlalchemy/fixtures.py

Lines 130 to 133 in 7cb57c0

	# Preserve close/commit/rollback methods
	connection.connection.force_close = connection.connection.close
	connection.connection.force_commit = connection.connection.commit
	connection.connection.force_rollback = connection.connection.rollback