Pytest fixture with scope “class” running on every method

Question

I'm trying to create a test environment with Pytest. The idea is to group test methods into classes.

For every class/group, I want to attach a config fixture that is going to be parametrized. So that I can run all the tests with "configuration A" and then all tests with "configuration B" and so on.

But also, I want a reset fixture, that can be executed before specific methods or all methods of a class.

The problem I have there is, once I apply my reset fixture (to a method or to a whole class), the config fixture seems to work in the function scope instead of the class scope. So, once I apply the reset fixture, the config fixture is called before/after every method in the class.

The following piece of code reproduces the problem:

import pytest
from pytest import *

@fixture(scope='class')
def config(request):
    print("\nconfiguring with %s" % request.param)
    yield
    print("\ncleaning up config")

@fixture(scope='function')
def reset():
    print("\nreseting")

@mark.parametrize("config", ["config-A", "config-B"], indirect=True)
#@mark.usefixtures("reset")
class TestMoreStuff(object):

    def test_a(self, config):
        pass

    def test_b(self, config):
        pass

    def test_c(self, config):
        pass

The test shows how the config fixture should work, being executed only once for the whole class. If you uncomment the usefixtures decoration, you can notice that the config fixture will be executed in every test method. Is it possible to use the reset fixture without triggering this behaviour?

This is actually a bug in Pytest 3.2.5: github.com/pytest-dev/pytest/issues/2938 — Gustavo Meira

Gustavo Meira Gustavo Meira · Accepted Answer · 2017-11-23T08:35:30

As I mentioned in a comment, that seems to be a bug in Pytest 3.2.5.

There's a workaround, which is to "force" the scope of a parametrization. So, in this case if you include the scope="class" in the parametrize decorator, you get the desired behaviour.

import pytest
from pytest import *

@fixture(scope='class')
def config(request):
    print("\nconfiguring with %s" % request.param)
    yield
    print("\ncleaning up config")

@fixture(scope='function')
def reset():
    print("\nreseting")

@mark.parametrize("config", ["config-A", "config-B"], indirect=True, scope="class")
@mark.usefixtures("reset")
class TestMoreStuff(object):

    def test_a(self, config):
        pass

    def test_b(self, config):
        pass

    def test_c(self, config):
        pass

Pytest fixture with scope “class” running on every method

2 Answers