Faster Django Tests

A long while ago, I discovered that running Django tests is much faster if you use SQLite, and if you turn off South (this now seems pretty obvious, but at the time was a bit of a revelation to me).

Since then, I’ve come across a better way of setting this up, to avoid having a test_settings.py:

# If manage.py test was called, use SQLite
import sys
if 'test' in sys.argv:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': j('test_sqlite.db')
        }
    }

That pretty well does what my old approach with test_settings.py, but instead of having to type:

python manage.py test --settings=test_settings

I can now just type:

python manage.py test

and the faster settings get loaded.

This morning I was perusing commits to Django on GitHub1, when I came across this one:

Documented that setting PASSWORD_HASHERS can speed up tests.

Turns out there’s another way to speed up tests if you’re authenticating users. Now my extra settings that I set if I’m running tests look like this:

# If manage.py test was called, use SQLite
import sys
if 'test' in sys.argv:
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.sqlite3',
            'NAME': j('test_sqlite.db')
        }
    }

    PASSWORD_HASHERS = (
        'django.contrib.auth.hashers.MD5PasswordHasher',
        'django.contrib.auth.hashers.SHA1PasswordHasher',
    )

Doing that took a sample run of the tests for my new project down from 3.6s to 1.0s, which is pretty good for 3 lines of code.

Django uses the first entry in the list for storing passwords, and the other entries in the list are also available. If you want Django’s test suite to pass, you’ll need to include the SHA1 hasher.

  1. This is probably something everyone who works with Django should do, it’s a great way of finding out what’s coming up, and also for stumbling across random tips like the one I’ve not quite got to yet.

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