How can we make Django tests faster?

Question

We are using Django 1.4 with PostgreSQL on Ubuntu 12.04. We have many tests, and the problem is that running the tests is very slow, I think because for each test the database is created from scratch. I want to make the tests faster by running them with the database in memory (not hard disk). How do I do it? Do you have any links or tutorials?

Answer 1

In Django 1.9 if you have a multi-core processor a great option is the flag:

--parallel

This requires you to pip install tblib but will let you run your unit tests simultaneously on multiple cores. (https://docs.djangoproject.com/en/1.10/ref/django-admin/#cmdoption-test-parallel)

Another great option for Django 1.8+ is the flag:

--keepdb

It reuses your test database, stopping the long wait time caused by creating a new test database each time you run tests. (https://docs.djangoproject.com/en/1.10/ref/django-admin/#cmdoption-test-keepdb

Answer 2

The best option is to have a separate settings file for your tests. In settings_test.py you tell it to use sqlite which by default use an in-memory database:

from base_settings import *

DATABASES = {
  'default': {
    'ENGINE': 'django.db.backends.sqlite3',
    'NAME': ':memory'
  }
}

And then run your tests by adding --settings=settings_test

See also the Django docs:
https://docs.djangoproject.com/en/dev/topics/testing/overview/#the-test-database