[pytest-dev] Parametrized autouse fixtures

[Bruno Oliveira]

Hi Thomas,

It seems the problem is that you are mixing xunit-style fixtures (by
implementing a setup_class classmethod) and pytest-style fixtures: they
currently don’t play well together, setup_* methods execute before all
other fixtures (see #517 <https://github.com/pytest-dev/pytest/issues/517>).
There are plans to fix that, but this scheduled for 3.6 only.

But there’s an easy workaround, just change your “setup_class” method into
a proper fixture instead:

class TestArchivesTestCaseMixin:

    @classmethod
    @pytest.fixture(autouse=True, params=['hg', 'git'], scope='class')
    def _configure_backend(cls, request):
        backend_alias = request.param
        Backend = vcs.get_backend(backend_alias)
        ...

Hope that helps.

Cheers,
Bruno.
​

On Mon, Mar 12, 2018 at 5:48 PM Thomas De Schampheleire <
patrickdepinguin at gmail.com> wrote:

> Hello,
>
> The Kallithea project is a repository hosting and review system,
> currently supporting git and hg. We currently have some test cases
> that need to be run for these two version control systems.
>
> Previously this was done with some Python magic, which was now
> simplified and made more explicit in commit:
>
> https://kallithea-scm.org/repos/kallithea/changeset/45a281a0f36ff59ffaa4aa0107fabfc1a6310251
>
> but I assume it can be made more automatic with pytest fixtures. I was
> thinking to use an autouse, parametrized fixture to set the backend to
> 'hg' and 'git' respectively. But I can't make it work.
>
> Here is the change I did on top of the mentioned commit:
>
> diff --git a/kallithea/tests/vcs/base.py b/kallithea/tests/vcs/base.py
> --- a/kallithea/tests/vcs/base.py
> +++ b/kallithea/tests/vcs/base.py
> @@ -5,6 +5,7 @@ InMemoryChangeset class is working prope
>  import os
>  import time
>  import datetime
> +import pytest
>
>  from kallithea.lib import vcs
>  from kallithea.lib.vcs.nodes import FileNode
> @@ -27,6 +28,11 @@ class _BackendTestMixin(object):
>      """
>      recreate_repo_per_test = True
>
> +    @pytest.fixture(autouse=True,
> +                    params=['hg', 'git'])
> +    def set_backend_alias(cls, request):
> +        cls.backend_alias = request.param
> +
>      @classmethod
>      def get_backend(cls):
>          return vcs.get_backend(cls.backend_alias)
> diff --git a/kallithea/tests/vcs/test_archives.py
> b/kallithea/tests/vcs/test_archives.py
> --- a/kallithea/tests/vcs/test_archives.py
> +++ b/kallithea/tests/vcs/test_archives.py
> @@ -14,7 +14,7 @@ from kallithea.tests.vcs.base import _Ba
>  from kallithea.tests.vcs.conf import TESTS_TMP_PATH
>
>
> -class ArchivesTestCaseMixin(_BackendTestMixin):
> +class TestArchivesTestCaseMixin(_BackendTestMixin):
>
>      @classmethod
>      def _get_commits(cls):
> @@ -95,11 +95,3 @@ class ArchivesTestCaseMixin(_BackendTest
>      def test_archive_prefix_with_leading_slash(self):
>          with pytest.raises(VCSError):
>              self.tip.fill_archive(prefix='/any')
> -
> -
> -class TestGitArchive(ArchivesTestCaseMixin):
> -    backend_alias = 'git'
> -
> -
> -class TestHgArchive(ArchivesTestCaseMixin):
> -    backend_alias = 'hg'
>
>
>
> but when running this I get:
>
> $  pytest kallithea/tests/vcs/test_archives.py
> Test session starts (platform: linux2, Python 2.7.14, pytest 3.4.2,
> pytest-sugar 0.9.1)
> benchmark: 3.1.1 (defaults: timer=time.time disable_gc=False
> min_rounds=5 min_time=0.000005 max_time=1.0 calibration_precision=10
> warmup=False warmup_iterations=100000)
> rootdir: /home/tdescham/repo/contrib/kallithea/kallithea-review,
> inifile: pytest.ini
> plugins: sugar-0.9.1, localserver-0.4.1, benchmark-3.1.1
>
>
> ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
> ERROR at setup of TestArchivesTestCaseMixin.test_archive_zip[hg]
> ―――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
> kallithea/tests/vcs/base.py:70: in setup_class
>     Backend = cls.get_backend()
> kallithea/tests/vcs/base.py:38: in get_backend
>     return vcs.get_backend(cls.backend_alias)
> E   AttributeError: type object 'TestArchivesTestCaseMixin' has no
> attribute 'backend_alias'
>
>
>                                                         7% ▊
>
> ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
> ERROR at setup of TestArchivesTestCaseMixin.test_archive_zip[git]
> ――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――――
> kallithea/tests/vcs/base.py:70: in setup_class
>     Backend = cls.get_backend()
> kallithea/tests/vcs/base.py:38: in get_backend
>     return vcs.get_backend(cls.backend_alias)
> E   AttributeError: type object 'TestArchivesTestCaseMixin' has no
> attribute 'backend_alias'
>
>
>                                                        14% █▌
>
> [..]
>
>
>
> So the parametrization seems to work because each test is run twice,
> but I can't seem to find the right way to set the backend_alias, such
> that a later call from a classmethod works correctly.
>
> I found some possibly useful magic by nicoddemus but could not make
> that work either:
> https://github.com/pytest-dev/pytest/issues/2618#issuecomment-318519875
>
> Is it possible to achieve what I want, without changing each test
> method to take a fixture explicitly?
>
> Thanks,
> Thomas
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