Testing migrations

MigrationTest.py

from django.apps import apps
from django.core.management import call_command
from django.db.models.signals import pre_migrate, post_migrate
from django.test import TransactionTestCase


# See https://www.caktusgroup.com/blog/2016/02/02/writing-unit-tests-django-migrations/
# for the original code.
class MigrationTest(TransactionTestCase):
    @property
    def app(self):
        return apps.get_containing_app_config(type(self).__module__).name

    migrate_from = None
    migrate_to = None

    def _reloadAppliedMigrations(self):
        self.executor.loader.build_graph()

    def setUp(self):
        assert self.migrate_from and self.migrate_to, \
            "TestCase '{}' must define migrate_from and migrate_to properties".format(type(self).__name__)

        # Reverse to the original migration
        call_command('migrate', self.app, self.migrate_from, verbosity=0)

        app_config = apps.get_app_config(self.app)

        pre_migrate.connect(self.setUpBeforeMigration, sender=app_config)
        post_migrate.connect(self.setUpAfterMigration, sender=app_config)
        call_command('migrate', self.app, self.migrate_to, verbosity=0)
        pre_migrate.disconnect(self.setUpBeforeMigration, sender=app_config)
        post_migrate.disconnect(self.setUpAfterMigration, sender=app_config)

    def setUpBeforeMigration(self, apps, **kwargs):
        pass

    def setUpAfterMigration(self, apps, **kwargs):
        """
        Do not override this method.
        """
        self.apps = apps

    def tearDown(self):
        call_command('migrate', verbosity=0)