How to create a model dynamically just for testing in djanjo

Question

I have a Django app that requires a settings attribute in the form of:

RELATED_MODELS = ('appname1.modelname1.attribute1',
                  'appname1.modelname2.attribute2', 
                  'appname2.modelname3.attribute3', ...)

Then hooks their post_save signal to update some other fixed model depending on the attributeN defined.

I would like to test this behaviour and tests should work even if this app is the only one in the project (except for its own dependencies, no other wrapper app need to be installed). How can I create and attach/register/activate mock models just for the test database? (or is it possible at all?)

Answer 1

Hello @kartik,

The basic idea is, make your tests an app, and add your tests to INSTALLED_APPS.

Here's an example:

$ ls common
__init__.py   admin.py      apps.py       fixtures      models.py     pagination.py tests         validators.py views.py

$ ls common/tests
__init__.py        apps.py            models.py          serializers.py     test_filter.py     test_pagination.py test_validators.py views.py

And I have different settings for different purposes, namely:

• settings/default.py: base settings file
• settings/production.py: for production
• settings/development.py: for development
• settings/testing.py: for testing.

And in settings/testing.py, you can modify INSTALLED_APPS:

settings/testing.py:

from default import *

DEBUG = True

INSTALLED_APPS += ['common', 'common.tests']

And make sure that you have set a proper label for your tests app, namely,

common/tests/apps.py

from django.apps import AppConfig


class CommonTestsConfig(AppConfig):
    name = 'common.tests'
    label = 'common_tests'

common/tests/__init__.py, set up proper AppConfig.

default_app_config = 'common.tests.apps.CommonTestsConfig'

Then, generate db migration by

python manage.py makemigrations --settings=<your_project_name>.settings.testing tests

Finally, you can run your test with param --settings=<your_project_name>.settings.testing.

If you use py.test, you can even drop a pytest.ini file along with django's manage.py.

py.test

[pytest]
DJANGO_SETTINGS_MODULE=kungfu.settings.testing

Hope it helps!

Thanks!