[3.2.x] Fixed #32643 -- Fixed decoding of messages in the pre-Django 3.2 format.

Thanks Jan Pieter Waagmeester for the report.

Regression in 2d6179c819010f6a9d00835d5893c4593c0b85a0.

Backport of 4511d1459810037b91faa5b506e4f75c77aa72be from main.

1 files changed, 5 insertions, 2 deletions

diff --git a/tests/messages_tests/test_cookie.py b/tests/messages_tests/test_cookie.py
index 9f82ce93e9..e62ab664fd 100644
--- a/tests/messages_tests/test_cookie.py
+++ b/tests/messages_tests/test_cookie.py
@@ -1,3 +1,4 @@
+import binascii
 import json
 import random
 
@@ -7,7 +8,7 @@ from django.contrib.messages.storage.base import Message
 from django.contrib.messages.storage.cookie import (
     CookieStorage, MessageDecoder, MessageEncoder,
 )
-from django.core.signing import get_cookie_signer
+from django.core.signing import b64_decode, get_cookie_signer
 from django.test import SimpleTestCase, override_settings
 from django.test.utils import ignore_warnings
 from django.utils.crypto import get_random_string
@@ -196,10 +197,12 @@ class CookieTests(BaseTests, SimpleTestCase):
         # RemovedInDjango41Warning: pre-Django 3.2 encoded messages will be
         # invalid.
         storage = self.storage_class(self.get_request())
-        messages = ['this', 'that']
+        messages = ['this', Message(0, 'Successfully signed in as admin@example.org')]
         # Encode/decode a message using the pre-Django 3.2 format.
         encoder = MessageEncoder()
         value = encoder.encode(messages)
+        with self.assertRaises(binascii.Error):
+            b64_decode(value.encode())
         signer = get_cookie_signer(salt=storage.key_salt)
         encoded_messages = signer.sign(value)
         decoded_messages = storage._decode(encoded_messages)