text: from django.apps import apps
  from django.test import TestCase
  
  
  class IsolatedModelsTestCase(TestCase):
      def setUp(self):
          # The unmanaged models need to be removed after the test in order to
          # prevent bad interactions with the flush operation in other tests.
          self._old_models = apps.app_configs['models'].models.copy()
  
      def tearDown(self):
          apps.app_configs['models'].models = self._old_models
          apps.all_models['models'] = self._old_models
          apps.clear_cache()
  