Python Testing with pytest

Using Multiple Fixture Levels

There’s a little bit of a problem with our test code right now. The problem is the tests both depend on the database being empty to start with, but they use the same database instance in the module-scope and session-scope versions.

The problem becomes very clear if we add a third test:

ch3/a/test_three.py

def test_three(cards_db):
    cards_db.add_card(cards.Card("first"))
    cards_db.add_card(cards.Card("second"))
    cards_db.add_card(cards.Card("third"))
    assert cards_db.count() == 3

It works fine by itself, but not when it’s run after test_count.py::test_two:

$ pytest -v test_three.py
========================== test session starts ==========================
collected 1 item

test_three.py::test_three ...