and on https://gist.github.com/TauPan/aec52e398d7288cb5a62895916182a9f (gistspection!)

from django.core.management import call_command from django.db import connection from django.db.migrations.executor import MigrationExecutor

import pytest

@pytest.fixture() def migration(request, transactional_db): # see https://gist.github.com/asfaltboy/b3e6f9b5d95af8ba2cc46f2ba6eae5e2 """ This fixture returns a helper object to test Django data migrations. The fixture returns an object with two methods; - before to initialize db to the state before the migration under test - after to execute the migration and bring db to the state after the migration The methods return old_apps and new_apps respectively; these can be used to initiate the ORM models as in the migrations themselves. For example:

    def test_foo_set_to_bar(migration):
        old_apps = migration.before([('my_app', '0001_inital')])

        Foo = old_apps.get_model('my_app', 'foo')
        Foo.objects.create(bar=False)

        assert Foo.objects.count() == 1
        assert Foo.objects.filter(bar=False).count() == Foo.objects.count()

        # executing migration
        new_apps = migration.apply([('my_app', '0002_set_foo_bar')])
        Foo = new_apps.get_model('my_app', 'foo')

        assert Foo.objects.filter(bar=False).count() == 0
        assert Foo.objects.filter(bar=True).count() == Foo.objects.count()

Based on: https://gist.github.com/blueyed/4fb0a807104551f103e6
"""
class Migrator(object):
    def before(self, targets):
        """ Specify app and starting migration names as in:
            before([('app', '0001_before')]) => app/migrations/0001_before.py
        """
        self.executor = MigrationExecutor(connection)
        # prepare state of db to before the migration ("migrate_from" state)
        self._old_apps = self.executor.migrate(targets).apps
        return self._old_apps

    def apply(self, targets):
        """ Migrate forwards to the "targets" migration """
        self.executor.loader.build_graph()  # reload.
        self._new_apps = self.executor.migrate(targets).apps
        return self._new_apps

# ensure to migrate forward migrated apps all the way after test
def migrate_to_end():
    call_command('migrate', verbosity=0)
request.addfinalizer(migrate_to_end)

return Migrator()