Skip migrations during Django tests

settings.py

INSTALLED_APPS = (
    # ...
)

# Skip migrations for tests
MIGRATION_MODULES = {
    # Assumes that all values in INSTALLED_APPS are simply a package containing
    # an application, not an application configuration class.
    app.split('.').pop(): '{0}.migrations_not_used_in_tests'.format(app) for app in INSTALLED_APPS
}