Great thing about Django is that configuration – settings.py is pure Python file.
This gives you power and expressiveness allowing to use conditions and expressions normally available in python script.
On past few projects, I’ve used ‘trick’ to automatically determine if ‘manage.py test’ was invoked
and use SQLite for unit testing instead of standard database used for production.
I thought it’s worth sharing, so here it is

The point is that if you have unit tests in your application(s) (which you should, believe me), running them on top of ‘standard’ database used for development or production (PostgreSQL, MySQL…) may be not the fastest thing around.
Considering you have _a lot_ of unit tests or initial_data fixtures, running them in memory would be great thing.
Let’s customize settings.py a little bit.

import sys
 
# is ./manage.py test ?
TEST = 'test' in sys.argv
 
if TEST:
    # in-memory SQLite used for testing
    DATABASES = {
            'default': {
                'ENGINE': 'django.db.backends.sqlite3',
                'NAME': ':memory:',
                }
            }
else:
    # devevelopment/production db
    DATABASES = {
            'default': {
                'ENGINE': 'django.db.backends.postgresql_psycopg2',
                'NAME': 'yourproductiondb',
                'USER': 'yourproductiondbuser',
                'PASSWORD': "secret_password",
                'HOST': 'localhost',
                'PORT': '',
                },
            }

So what we did:
- automatically determine if ‘./manage.py test’ was invoked and store that in TEST variable
- if TEST is True, use SQLite in-memory database instead of your production/development database

Assuming your tests and models are fine with SQLite, you can save some time when periodically running unit tests,
which is worth some hacking

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