Refs #17001 -- Added a test for custom prefetch related queryset on generic relations.

tests/prefetch_related/tests.py

@@ -836,6 +836,19 @@ class GenericRelationTests(TestCase):
             self.assertEqual(sorted([i.tag for i in bookmark.tags.all()]), ["django", "python"])
             self.assertEqual([i.tag for i in bookmark.favorite_tags.all()], ["python"])
 
+    def test_custom_queryset(self):
+        bookmark = Bookmark.objects.create(url='http://www.djangoproject.com/')
+        django_tag = TaggedItem.objects.create(content_object=bookmark, tag='django')
+        TaggedItem.objects.create(content_object=bookmark, tag='python')
+
+        with self.assertNumQueries(2):
+            bookmark = Bookmark.objects.prefetch_related(
+                Prefetch('tags', TaggedItem.objects.filter(tag='django')),
+            ).get()
+
+        with self.assertNumQueries(0):
+            self.assertEqual(list(bookmark.tags.all()), [django_tag])
+
 
 class MultiTableInheritanceTest(TestCase):