Made migrations tests write to a temporary directory.

import os

import shutil

import tempfile

from contextlib import contextmanager

from importlib import import_module

from django.apps import apps

from django.db import connection

from django.test import TransactionTestCase

from django.utils._os import upath

from django.test.utils import extend_sys_path

from django.utils.module_loading import module_dir

class MigrationTestBase(TransactionTestCase):

    """

    available_apps = ["migrations"]

    test_dir = os.path.abspath(os.path.dirname(upath(__file__)))

    def get_table_description(self, table):

        with connection.cursor() as cursor:

    def assertFKNotExists(self, table, columns, to, value=True):

        return self.assertFKExists(table, columns, to, False)

    @contextmanager

    def temporary_migration_module(self, app_label='migrations', module=None):

        """

        Allows testing management commands in a temporary migrations module.

        Wrap all invocations to makemigrations and squashmigrations with this

        context manager in order to avoid creating migration files in your

        source tree inadvertently.

        Takes the application label that will be passed to makemigrations or

        squashmigrations and the Python path to a migrations module.

        The migrations module is used as a template for creating the temporary

        migrations module. If it isn't provided, the application's migrations

        module is used, if it exists.

        Returns the filesystem path to the temporary migrations module.

        """

        temp_dir = tempfile.mkdtemp()

        try:

            target_dir = tempfile.mkdtemp(dir=temp_dir)

            with open(os.path.join(target_dir, '__init__.py'), 'w'):

                pass

            target_migrations_dir = os.path.join(target_dir, 'migrations')

            if module is None:

                module = apps.get_app_config(app_label).name + '.migrations'

            try:

                source_migrations_dir = module_dir(import_module(module))

            except (ImportError, ValueError):

                pass

            else:

                shutil.copytree(source_migrations_dir, target_migrations_dir)

            with extend_sys_path(temp_dir):

                new_module = os.path.basename(target_dir) + '.migrations'

                with self.settings(MIGRATION_MODULES={app_label: new_module}):

                    yield target_migrations_dir

        finally:

            shutil.rmtree(temp_dir)