Fixed #31842 -- Added DEFAULT_HASHING_ALGORITHM transitional setting.

It's a transitional setting helpful in migrating multiple instance of
the same project to Django 3.1+.

Thanks Markus Holtermann for the report and review, Florian
Apolloner for the implementation idea and review, and Carlton Gibson
for the review.

1 files changed, 17 insertions, 1 deletions

diff --git a/tests/signing/tests.py b/tests/signing/tests.py
index df7cad9747..835ca4d6b2 100644
--- a/tests/signing/tests.py
+++ b/tests/signing/tests.py
@@ -2,8 +2,9 @@ import datetime
 
 from django.core import signing
 from django.test import SimpleTestCase
-from django.test.utils import freeze_time
+from django.test.utils import freeze_time, ignore_warnings
 from django.utils.crypto import InvalidAlgorithm
+from django.utils.deprecation import RemovedInDjango40Warning
 
 
 class TestSigner(SimpleTestCase):
@@ -52,6 +53,14 @@ class TestSigner(SimpleTestCase):
             'VzO9_jVu7R-VkqknHYNvw',
         )
 
+    @ignore_warnings(category=RemovedInDjango40Warning)
+    def test_default_hashing_algorithm(self):
+        signer = signing.Signer('predictable-secret', algorithm='sha1')
+        signature_sha1 = signer.signature('hello')
+        with self.settings(DEFAULT_HASHING_ALGORITHM='sha1'):
+            signer = signing.Signer('predictable-secret')
+            self.assertEqual(signer.signature('hello'), signature_sha1)
+
     def test_invalid_algorithm(self):
         signer = signing.Signer('predictable-secret', algorithm='whatever')
         msg = "'whatever' is not an algorithm accepted by the hashlib module."
@@ -134,6 +143,13 @@ class TestSigner(SimpleTestCase):
         signed = 'ImEgc3RyaW5nIFx1MjAyMCI:1k1beT:ZfNhN1kdws7KosUleOvuYroPHEc'
         self.assertEqual(signing.loads(signed), value)
 
+    @ignore_warnings(category=RemovedInDjango40Warning)
+    def test_dumps_loads_default_hashing_algorithm_sha1(self):
+        value = 'a string \u2020'
+        with self.settings(DEFAULT_HASHING_ALGORITHM='sha1'):
+            signed = signing.dumps(value)
+        self.assertEqual(signing.loads(signed), value)
+
     def test_decode_detects_tampering(self):
         "loads should raise exception for tampered objects"
         transforms = (