Refs #20349 -- Avoided loading testing libraries when not needed.

[collinanderson]

This avoids loading django.test, unittest, and xml libraries when not needed.

See https://code.djangoproject.com/ticket/20349

This should give slightly faster startup time and slightly lower memory usage.

[charettes]

I so wish there was an easy way to test for that to prevent future regressions.

What if we called python -m django --settings=settings_install_all_contrib_apps mng_cmd_asserts_no_django_test in a subprocess.

Where the management command is placed in a test app referenced by settings_install_all_contrib_apps.INSTALLED_APPS and asserts that 'django.test' not in sys.modules?

[collinanderson]

Makes sense, but I might need some help making that test. Where should it go? (admin_scripts/tests.py?) Is there already a settings_install_all_contrib_apps somewhere?

[charettes]

Where should it go? (admin_scripts/tests.py?)

I'm not sure of where it should live. Maybe in test_utils or in a new test_modules one?

Is there already a settings_install_all_contrib_apps somewhere?

It doesn't exist yet but it could live as a module in the test app? I guess it could have all DB backend compatible contrib apps installed.

[ngnpope]

I so wish there was an easy way to test for that to prevent future regressions.

Maybe import-linter could be used? There are a whole bunch of other import patterns that we've tidied up in the past which would be nice to enforce, e.g. #11689.

[felixxm]

@collinanderson Thanks 👍

[collinanderson]

Thanks. Yeah, I'm not super good at tests.