1 files changed, 25 insertions, 0 deletions
diff --git a/tests/auth_tests/test_models.py b/tests/auth_tests/test_models.py
index 41f822fdc7..19454ade65 100644
--- a/tests/auth_tests/test_models.py
+++ b/tests/auth_tests/test_models.py
@@ -1,5 +1,7 @@
 from unittest import mock
 
+from asgiref.sync import sync_to_async
+
 from django.conf.global_settings import PASSWORD_HASHERS
 from django.contrib.auth import get_user_model
 from django.contrib.auth.backends import ModelBackend
@@ -312,6 +314,29 @@ class AbstractUserTestCase(TestCase):
         finally:
             hasher.iterations = old_iterations
 
+    @override_settings(PASSWORD_HASHERS=PASSWORD_HASHERS)
+    async def test_acheck_password_upgrade(self):
+        user = await sync_to_async(User.objects.create_user)(
+            username="user", password="foo"
+        )
+        initial_password = user.password
+        self.assertIs(await user.acheck_password("foo"), True)
+        hasher = get_hasher("default")
+        self.assertEqual("pbkdf2_sha256", hasher.algorithm)
+
+        old_iterations = hasher.iterations
+        try:
+            # Upgrade the password iterations.
+            hasher.iterations = old_iterations + 1
+            with mock.patch(
+                "django.contrib.auth.password_validation.password_changed"
+            ) as pw_changed:
+                self.assertIs(await user.acheck_password("foo"), True)
+                self.assertEqual(pw_changed.call_count, 0)
+            self.assertNotEqual(initial_password, user.password)
+        finally:
+            hasher.iterations = old_iterations
+
 
 class CustomModelBackend(ModelBackend):
     def with_perm(