Refs #32508 -- Raised ImproperlyConfigured instead of using "assert" in SessionStorage.

django/contrib/messages/storage/session.py

@@ -4,6 +4,7 @@ from django.contrib.messages.storage.base import BaseStorage
 from django.contrib.messages.storage.cookie import (
     MessageDecoder, MessageEncoder,
 )
+from django.core.exceptions import ImproperlyConfigured
 
 
 class SessionStorage(BaseStorage):
@@ -13,10 +14,12 @@ class SessionStorage(BaseStorage):
     session_key = '_messages'
 
     def __init__(self, request, *args, **kwargs):
-        assert hasattr(request, 'session'), "The session-based temporary "\
-            "message storage requires session middleware to be installed, "\
-            "and come before the message middleware in the "\
-            "MIDDLEWARE list."
+        if not hasattr(request, 'session'):
+            raise ImproperlyConfigured(
+                'The session-based temporary message storage requires session '
+                'middleware to be installed, and come before the message '
+                'middleware in the MIDDLEWARE list.'
+            )
         super().__init__(request, *args, **kwargs)
 
     def _get(self, *args, **kwargs):

tests/messages_tests/test_session.py

@@ -1,6 +1,7 @@
 from django.contrib.messages import constants
 from django.contrib.messages.storage.base import Message
 from django.contrib.messages.storage.session import SessionStorage
+from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpRequest
 from django.test import TestCase
 from django.utils.safestring import SafeData, mark_safe
@@ -41,7 +42,7 @@ class SessionTests(BaseTests, TestCase):
             'middleware to be installed, and come before the message '
             'middleware in the MIDDLEWARE list.'
         )
-        with self.assertRaisesMessage(AssertionError, msg):
+        with self.assertRaisesMessage(ImproperlyConfigured, msg):
             self.storage_class(HttpRequest())
 
     def test_get(self):