text: """
  Test the bulk email opt out view.
  """
  
  import ddt
  import pytest
  from django.http import Http404
  from django.test.client import RequestFactory
  from django.test.utils import override_settings
  from django.urls import reverse
  
  from common.djangoapps.student.tests.factories import UserFactory
  from lms.djangoapps.bulk_email.models import Optout
  from lms.djangoapps.bulk_email.views import opt_out_email_updates
  from lms.djangoapps.discussion.notification_prefs.views import UsernameCipher
  from openedx.core.lib.tests import attr
  from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
  from xmodule.modulestore.tests.factories import CourseFactory
  
  
  @attr(shard=1)
  @ddt.ddt
  @override_settings(SECRET_KEY="test secret key")
  class OptOutEmailUpdatesViewTest(ModuleStoreTestCase):
      """
      Check the opt out email functionality.
      """
      def setUp(self):
          super().setUp()
          self.user = UserFactory.create(username="testuser1", email='test@example.com')
          self.course = CourseFactory.create(run='testcourse1', display_name='Test Course Title')
          self.token = UsernameCipher.encrypt('testuser1')
          self.request_factory = RequestFactory()
          self.url = reverse('bulk_email_opt_out', args=[self.token, str(self.course.id)])
  
          # Ensure we start with no opt-out records
          assert Optout.objects.count() == 0
  
      def test_opt_out_email_confirm(self):
          """
          Ensure that the default GET view asks for confirmation.
          """
          response = self.client.get(self.url)
          self.assertContains(response, "confirm unsubscribe from")
          assert Optout.objects.count() == 0
  
      def test_opt_out_email_unsubscribe(self):
          """
          Ensure that the POSTing "confirm" creates the opt-out record.
          """
          response = self.client.post(self.url, {'unsubscribe': True})
          self.assertContains(response, "You have successfully unsubscribed from")
          assert Optout.objects.count() == 1
  
      def test_opt_out_email_cancel(self):
          """
          Ensure that the POSTing "cancel" does not create the opt-out record
          """
          response = self.client.post(self.url)
          self.assertContains(response, "You have not been unsubscribed from")
          assert Optout.objects.count() == 0
  
      @ddt.data(
          ("ZOMG INVALID BASE64 CHARS!!!", "base64url", False),
          ("Non-ASCII\xff".encode(), "base64url", False),
          ("D6L8Q01ztywqnr3coMOlq0C3DG05686lXX_1ArEd0ok", "base64url", False),
          ("AAAAAAAAAAA=", "initialization_vector", False),
          ("nMXVK7PdSlKPOovci-M7iqS09Ux8VoCNDJixLBmj", "aes", False),
          ("AAAAAAAAAAAAAAAAAAAAAMoazRI7ePLjEWXN1N7keLw=", "padding", False),
          ("AAAAAAAAAAAAAAAAAAAAACpyUxTGIrUjnpuUsNi7mAY=", "username", False),
          ("_KHGdCAUIToc4iaRGy7K57mNZiiXxO61qfKT08ExlY8=", "course", 'course-v1:testcourse'),
      )
      @ddt.unpack
      def test_unsubscribe_invalid_token(self, token, message, course):
          """
          Make sure that view returns 404 in case token is not valid
          """
          request = self.request_factory.get("dummy")
          with pytest.raises(Http404) as err:
              opt_out_email_updates(request, token, course)
              assert message in err
  