What to do when a py.test hangs silently?

Question

While using py.test, I have some tests that run fine with SQLite but hang silently when I switch to Postgresql. How would I go about debugging something like that? Is there a "verbose" mode I can run my tests in, or set a breakpoint ? More generally, what is the standard plan of attack when pytest stalls silently? I've tried using the pytest-timeout, and ran the test with $ py.test --timeout=300, but the tests still hang with no activity on the screen whatsoever

Answer 1

I ran into the same SQLite/Postgres problem with Flask and SQLAlchemy, similar to Gordon Fierce. However, my solution was different. Postgres is strict about table locks and connections, so explicitly closing the session connection on teardown solved the problem for me.

My working code:

@pytest.yield_fixture(scope='function')
def db(app):
    # app is an instance of a flask app, _db a SQLAlchemy DB
    _db.app = app
    with app.app_context():
        _db.create_all()

    yield _db

    # Explicitly close DB connection
    _db.session.close()

    _db.drop_all()

Reference: SQLAlchemy