Document that ManifestStaticFilesStorage shouldn't be used during testing

[Nathan Vander Wilt]

I recently switched a project to the ManifestStaticFilesStorage backend for the "permacacheable" URLs it gives to resources that may change. However, this seems to have broken some of my Selenium tests, which use StaticLiveServerTestCase for the browser resources.

Now when I try to run my tests, they fail. I get a bunch of stacktraces that read

ValueError: The file 'images/favicon.ico' could not be found with <django.contrib.staticfiles.storage.ManifestStaticFilesStorage object at 0x1037ed290>.

Running ./manage.py collectstatic before the tests makes the problem go away, but this is a poor workaround (it leaves stale resources which become confusing during development). Accessing the site works just fine via ./manage.py runserver, but is it expected for tests not to work in this configuration?

[Nathan Vander Wilt]

Looks like the immediate cause is ​this:

Regardless of the value of the DEBUG setting in your configuration file, all Django tests run with DEBUG=False.

The HashedFilesMixin relies on debug mode to leave URLs alone, so when that is disabled it expects the manifest file generated by the collectstatic management command.

At this point, the cleanest workaround idea I've found will be to use the override_settings decorator to set it back (​as described on here) on every method in my Selenium test suite.

[Nathan Vander Wilt]

This was actually breaking all my tests, irregardless of being based on StaticLiveServerTestCase or not. A more robust workaround is to revert the STATICFILES_STORAGE setting during tests. I now put this atop my tests.py file to work around the situation:

# WORKAROUND: https://code.djangoproject.com/ticket/24364 by reverting to default storage
from django.conf import settings, global_settings
settings.STATICFILES_STORAGE = global_settings.STATICFILES_STORAGE

[Tim Graham]

I asked Jannis about this (author of ManifestStaticFilesStorage) and he said that you shouldn't use ManifestStaticFilesStorage during tests, so I'll triage this as a documentation issue.

[Aksel]

This is my first commit to Django so please bear with me.

I wrote a simple piece of documentation for this issue. I'm attaching the diff file to this ticket.

Furthermore, I've sent a pull request to Django's stable/1.7.x branch.

I'm eager to hear if I've done all steps correctly.

[Aksel]

Diff file for ticket 24364

[Aksel]

Diff for ticket #24364

[Tim Graham <timograham@…>]

In b4d8b16:

Fixed #24364 -- Doc'ed that ManifestStaticFileStorage shouldn't be used during testing.

[Tim Graham <timograham@…>]

In fee18ce:

[1.8.x] Fixed #24364 -- Doc'ed that ManifestStaticFileStorage shouldn't be used during testing.

Backport of b4d8b16e5109170614ba505e36f60c2ad64dafc2 from master

[Tim Graham <timograham@…>]

In 8084a68:

[1.7.x] Fixed #24364 -- Doc'ed that ManifestStaticFileStorage shouldn't be used during testing.

Backport of b4d8b16e5109170614ba505e36f60c2ad64dafc2 from master