Incorrect finalize/cleanup order of fixtures when using request.getfixturevalue()

[jbeluch]

Here's a test file that can be run to verify the issue: http://hastebin.com/exozenenas.py

Basically, when you have 2 fixtures, one session and one function scoped that both require another session scoped fixture via request.getfixturevalue(), the cleanup order of the fixtures is incorrect. The shared resource gets cleaned up before the session fixture that relies on it.

[jbeluch]

import pytest


@pytest.fixture(scope='session')
def resource():
    yield
    print 'cleanup resource'


@pytest.fixture(scope='session')
def sess(request):
    request.getfixturevalue('resource')
    yield
    print 'cleanup sess'


@pytest.fixture(scope='function')
def func(request):
    request.getfixturevalue('resource')
    yield
    print 'cleanup func'



@pytest.fixture(scope='session')
def resource2():
    yield
    print 'cleanup resource2'

@pytest.fixture(scope='session')
def sess2(resource2):
    yield
    print 'cleanup sess2'


@pytest.fixture(scope='function')
def func2(resource2):
    yield
    print 'cleanup func2'


def test_sess(sess):
    pass

def test_func(func):
    pass

def test_sess2(sess2):
    pass

def test_func2(func2):
    pass


# Output below, when using request.getfixturevalue() in a fixture, the cleanup order of fixtures is incorrect (resource is cleaned up before sess)
'''
Output:
$ py.test test_fixtures.py  -vs
==================================================================================================================================================== test session starts =====================================================================================================================================================
platform darwin -- Python 2.7.10, pytest-3.0.1, py-1.4.31, pluggy-0.3.1
rootdir: /tmp, inifile: tox.ini
collected 4 items

tests/test_fixtures.py ..cleanup func
..cleanup func2
cleanup sess2
cleanup resource2
cleanup resource
cleanup sess
'''

[nicoddemus]

Thanks!

For reference, the example can be reduced further:

Using getfixturevalue:

import pytest


@pytest.fixture(scope='session')
def resource():
    r = [1]
    yield r
    del r[0]

@pytest.fixture(scope='session')
def sess(request):
    r = request.getfixturevalue('resource')
    yield
    assert r == [1]

@pytest.fixture(scope='function')
def func(request):
    request.getfixturevalue('resource')
    yield

def test_sess(sess):
    pass

def test_func(func):
    pass

This fails with:

_________________________________ ERROR at teardown of test_func __________________________________

request = <SubRequest 'sess' for <Function test_sess>>

    @pytest.fixture(scope='session')
    def sess(request):
        r = request.getfixturevalue('resource')
        yield
>       assert r == [1]
E       assert [] == [1]

.tmp\test-fixtures.py:15: AssertionError

Explicit dependency:

import pytest

@pytest.fixture(scope='session')
def resource():
    r = [1]
    yield r
    del r[0]

@pytest.fixture(scope='session')
def sess(request, resource):
    yield
    assert resource == [1]

@pytest.fixture(scope='function')
def func(resource):
    yield

def test_sess(sess):
    pass

def test_func(func):
    pass

This dependency passes.

TBH, I'm not sure how hard it is to fix this due to how resource caching and cleaning up is configured in the current architecture. 😬