Fails but maybe a start for how to test this

src/paperless/tests/test_adapter.py

@@ -1,6 +1,10 @@
+from contextvars import ContextVar
+from unittest import mock
+
 from allauth.account.adapter import get_adapter
 from allauth.socialaccount.adapter import get_adapter as get_social_adapter
 from django.conf import settings
+from django.http import HttpRequest
 from django.test import TestCase
 from django.urls import reverse
 
@@ -17,6 +21,32 @@ class TestCustomAccountAdapter(TestCase):
         settings.ACCOUNT_ALLOW_SIGNUPS = False
         self.assertFalse(adapter.is_open_for_signup(None))
 
+    @mock.patch("allauth.core.context._request_var")
+    def test_is_safe_url(self, mock_request_var):
+        request = HttpRequest()
+        request.get_host = mock.Mock(return_value="example.com")
+        mock_request_var.return_value = ContextVar("request", default=request)
+        adapter = get_adapter()
+
+        settings.ALLOWED_HOSTS = ["*"]
+        # True because request host is same
+        url = "https://example.com"
+        self.assertTrue(adapter.is_safe_url(url))
+
+        url = "https://evil.com"
+        # False despite wildcard because request host is different
+        self.assertFalse(adapter.is_safe_url(url))
+
+        settings.ALLOWED_HOSTS = ["example.com"]
+        url = "https://example.com"
+        # True because request host is same
+        self.assertTrue(adapter.is_safe_url(url))
+
+        settings.ALLOWED_HOSTS = ["*", "example.com"]
+        url = "//evil.com"
+        # False because request host is not in allowed hosts
+        self.assertFalse(adapter.is_safe_url(url))
+
 
 class TestCustomSocialAccountAdapter(TestCase):
     def test_is_open_for_signup(self):