[4.1.x] Fixed #33919 -- Fixed adding AutoFields on PostgreSQL.

Thanks Jack Calvin Brown for the report.

Regression in 2eea361eff58dd98c409c5227064b901f41bd0d6.
Backport of 5c803bc0702511c8bc05e9db600367a465514f82 from main

1 files changed, 25 insertions, 0 deletions

diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index 7bd62a2f66..94e9c8e0d7 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -792,6 +792,31 @@ class SchemaTests(TransactionTestCase):
         # Introspection treats BLOBs as TextFields
         self.assertEqual(columns["bits"][0], "TextField")
 
+    @isolate_apps("schema")
+    def test_add_auto_field(self):
+        class AddAutoFieldModel(Model):
+            name = CharField(max_length=255, primary_key=True)
+
+            class Meta:
+                app_label = "schema"
+
+        with connection.schema_editor() as editor:
+            editor.create_model(AddAutoFieldModel)
+        self.isolated_local_models = [AddAutoFieldModel]
+        old_field = AddAutoFieldModel._meta.get_field("name")
+        new_field = CharField(max_length=255)
+        new_field.set_attributes_from_name("name")
+        new_field.model = AddAutoFieldModel
+        with connection.schema_editor() as editor:
+            editor.alter_field(AddAutoFieldModel, old_field, new_field)
+        new_auto_field = AutoField(primary_key=True)
+        new_auto_field.set_attributes_from_name("id")
+        new_auto_field.model = AddAutoFieldModel()
+        with connection.schema_editor() as editor:
+            editor.add_field(AddAutoFieldModel, new_auto_field)
+        # Crashes on PostgreSQL when the GENERATED BY suffix is missing.
+        AddAutoFieldModel.objects.create(name="test")
+
     def test_remove_field(self):
         with connection.schema_editor() as editor:
             editor.create_model(Author)