test: verify exempt-user session persistence via Session model, not dashboard view

The dashboard-view GET added to test_single_session_exempt_user passed
locally but failed in CI's shared-with-cms-1 job (400 instead of 200),
likely from unrelated view-layer state (MFE redirect flags, site config)
picked up when run alongside the rest of that shard. Assert against
Session.objects directly instead -- that's the actual mechanism
set_login_session uses to evict a session, so it verifies the same
thing without depending on the dashboard view rendering successfully.

Author: blarghmatey

openedx/core/djangoapps/user_authn/views/tests/test_login.py

@@ -13,6 +13,7 @@
 import ddt
 from django.conf import settings
 from django.contrib.auth.models import Group, User  # pylint: disable=imported-auth-user
+from django.contrib.sessions.models import Session
 from django.core import mail
 from django.core.cache import cache
 from django.http import HttpResponse
@@ -682,17 +683,10 @@ def test_single_session_exempt_user(self):
             # session is ever deleted.
             assert 'session_id' not in self.user.profile.get_meta()
 
-            try:
-                # this test can be run with either lms or studio settings
-                # since studio does not have a dashboard url, we should
-                # look for another url that is login_required, in that case
-                url = reverse('dashboard')
-            except NoReverseMatch:
-                url = reverse('upload_transcripts')
-            response = client1.get(url)
-            # client1 remains authenticated; the exempt user's first session
-            # was not evicted by the second login.
-            assert response.status_code == 200
+            # client1's Django session itself was never evicted -- this is
+            # the actual mechanism set_login_session uses to end a session,
+            # so it stays valid independent of what profile meta records.
+            assert Session.objects.filter(session_key=client1.session.session_key).exists()
 
     @patch.dict("django.conf.settings.FEATURES", {'PREVENT_CONCURRENT_LOGINS': True})
     def test_single_session_exempt_group(self):