Refs #28586 -- Split descriptor from GenericForeignKey.

This makes GenericForeignKey more similar to other fields which act as
descriptors, preparing it to add “fetcher protocol” support in a clear and
consistent way.

2 files changed, 25 insertions, 12 deletions

diff --git a/tests/contenttypes_tests/test_checks.py b/tests/contenttypes_tests/test_checks.py
index 50730c5a1d..c33920f6b7 100644
--- a/tests/contenttypes_tests/test_checks.py
+++ b/tests/contenttypes_tests/test_checks.py
@@ -19,15 +19,17 @@ class GenericForeignKeyTests(SimpleTestCase):
             object_id = models.PositiveIntegerField()
             content_object = GenericForeignKey()
 
+        field = TaggedItem._meta.get_field("content_object")
+
         expected = [
             checks.Error(
                 "The GenericForeignKey content type references the nonexistent "
                 "field 'TaggedItem.content_type'.",
-                obj=TaggedItem.content_object,
+                obj=field,
                 id="contenttypes.E002",
             )
         ]
-        self.assertEqual(TaggedItem.content_object.check(), expected)
+        self.assertEqual(field.check(), expected)
 
     def test_invalid_content_type_field(self):
         class Model(models.Model):
@@ -35,8 +37,10 @@ class GenericForeignKeyTests(SimpleTestCase):
             object_id = models.PositiveIntegerField()
             content_object = GenericForeignKey("content_type", "object_id")
 
+        field = Model._meta.get_field("content_object")
+
         self.assertEqual(
-            Model.content_object.check(),
+            field.check(),
             [
                 checks.Error(
                     "'Model.content_type' is not a ForeignKey.",
@@ -44,7 +48,7 @@ class GenericForeignKeyTests(SimpleTestCase):
                         "GenericForeignKeys must use a ForeignKey to "
                         "'contenttypes.ContentType' as the 'content_type' field."
                     ),
-                    obj=Model.content_object,
+                    obj=field,
                     id="contenttypes.E003",
                 )
             ],
@@ -58,8 +62,10 @@ class GenericForeignKeyTests(SimpleTestCase):
             object_id = models.PositiveIntegerField()
             content_object = GenericForeignKey("content_type", "object_id")
 
+        field = Model._meta.get_field("content_object")
+
         self.assertEqual(
-            Model.content_object.check(),
+            field.check(),
             [
                 checks.Error(
                     "'Model.content_type' is not a ForeignKey to "
@@ -68,7 +74,7 @@ class GenericForeignKeyTests(SimpleTestCase):
                         "GenericForeignKeys must use a ForeignKey to "
                         "'contenttypes.ContentType' as the 'content_type' field."
                     ),
-                    obj=Model.content_object,
+                    obj=field,
                     id="contenttypes.E004",
                 )
             ],
@@ -80,13 +86,15 @@ class GenericForeignKeyTests(SimpleTestCase):
             # missing object_id field
             content_object = GenericForeignKey()
 
+        field = TaggedItem._meta.get_field("content_object")
+
         self.assertEqual(
-            TaggedItem.content_object.check(),
+            field.check(),
             [
                 checks.Error(
                     "The GenericForeignKey object ID references the nonexistent "
                     "field 'object_id'.",
-                    obj=TaggedItem.content_object,
+                    obj=field,
                     id="contenttypes.E001",
                 )
             ],
@@ -98,12 +106,14 @@ class GenericForeignKeyTests(SimpleTestCase):
             object_id = models.PositiveIntegerField()
             content_object_ = GenericForeignKey("content_type", "object_id")
 
+        field = Model._meta.get_field("content_object_")
+
         self.assertEqual(
-            Model.content_object_.check(),
+            field.check(),
             [
                 checks.Error(
                     "Field names must not end with an underscore.",
-                    obj=Model.content_object_,
+                    obj=field,
                     id="fields.E001",
                 )
             ],
diff --git a/tests/contenttypes_tests/test_fields.py b/tests/contenttypes_tests/test_fields.py
index c2b12b58bc..76830c3af3 100644
--- a/tests/contenttypes_tests/test_fields.py
+++ b/tests/contenttypes_tests/test_fields.py
@@ -15,13 +15,16 @@ class GenericForeignKeyTests(TestCase):
         class Model(models.Model):
             field = GenericForeignKey()
 
-        self.assertEqual(str(Model.field), "contenttypes_tests.Model.field")
+        field = Model._meta.get_field("field")
+
+        self.assertEqual(str(field), "contenttypes_tests.Model.field")
 
     def test_get_content_type_no_arguments(self):
+        field = Answer._meta.get_field("question")
         with self.assertRaisesMessage(
             Exception, "Impossible arguments to GFK.get_content_type!"
         ):
-            Answer.question.get_content_type()
+            field.get_content_type()
 
     def test_get_object_cache_respects_deleted_objects(self):
         question = Question.objects.create(text="Who?")