new_contents: from wizard_builder.models import QuestionPage, SingleLineText
  
  from django.test import TestCase
  
  
  class InheritenceTest(TestCase):
  
      def test_site_passed_to_question_page_manager(self):
          page = QuestionPage.objects.create()
          question = SingleLineText.objects.create(page_id=page.id)
          self.assertTrue(isinstance(question.page, QuestionPage))
  
subject: add inheritence test