From c8250ef361dcb4c7ed76632e4308c6db22da77d0 Mon Sep 17 00:00:00 2001
From: Mariusz Felisiak <felisiak.mariusz@gmail.com>
Date: Wed, 11 Sep 2019 13:40:49 +0200
Subject: [PATCH] Refs #27338 -- Added tests for altering CharField with
 primary_key=True to AutoField on PostgreSQL.

Fixed in 91b2bc3e70be2632baad86488fb03cf02848b5b6.
---
 tests/schema/tests.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/tests/schema/tests.py b/tests/schema/tests.py
index 41c1cd5120..4f3c2b361b 100644
--- a/tests/schema/tests.py
+++ b/tests/schema/tests.py
@@ -304,6 +304,24 @@ class SchemaTests(TransactionTestCase):
             editor.alter_field(AuthorTextFieldWithIndex, old_field, new_field, strict=True)
         self.assertForeignKeyExists(AuthorTextFieldWithIndex, 'text_field_id', 'schema_author')
 
+    @isolate_apps('schema')
+    def test_char_field_pk_to_auto_field(self):
+        class Foo(Model):
+            id = CharField(max_length=255, primary_key=True)
+
+            class Meta:
+                app_label = 'schema'
+
+        with connection.schema_editor() as editor:
+            editor.create_model(Foo)
+        self.isolated_local_models = [Foo]
+        old_field = Foo._meta.get_field('id')
+        new_field = AutoField(primary_key=True)
+        new_field.set_attributes_from_name('id')
+        new_field.model = Foo
+        with connection.schema_editor() as editor:
+            editor.alter_field(Foo, old_field, new_field, strict=True)
+
     @skipUnlessDBFeature('supports_foreign_keys')
     def test_fk_to_proxy(self):
         "Creating a FK to a proxy model creates database constraints."