I've met some problem with running tests using FastAPI+SQLAlchemy and PostgreSQL, which leads to lots of errors (however, it works well on SQLite). So I created a repo with MVP app and Pytest on Docker Compose testing.

The basic error is InterfaceError('cannot perform operation: another operation is in progress'). This may be related to the app/DB initialization, though I checked that all the operations get performed sequentially. Also I tried to use single instance of TestClient for the all tests, but got no results.

Feel free to tell a solution :)

docker-compose -f docker-compose.test.yml up --build

Or:

pip install -r requirements.txt
pytest tests.py
# But this will use SQLite by default