Fixed #24870 -- Added --update option to makemigrations command.

tests/migrations/test_commands.py

@@ -2584,6 +2584,108 @@ class MakeMigrationsTests(MigrationTestBase):
             out_value = out.getvalue()
             self.assertIn("0003_auto", out_value)
 
+    def test_makemigrations_update(self):
+        with self.temporary_migration_module(
+            module="migrations.test_migrations"
+        ) as migration_dir:
+            migration_file = os.path.join(migration_dir, "0002_second.py")
+            with open(migration_file) as fp:
+                initial_content = fp.read()
+
+            with captured_stdout() as out:
+                call_command("makemigrations", "migrations", update=True)
+            self.assertFalse(
+                any(
+                    filename.startswith("0003")
+                    for filename in os.listdir(migration_dir)
+                )
+            )
+            self.assertIs(os.path.exists(migration_file), False)
+            new_migration_file = os.path.join(
+                migration_dir,
+                "0002_delete_tribble_author_rating_modelwithcustombase_and_more.py",
+            )
+            with open(new_migration_file) as fp:
+                self.assertNotEqual(initial_content, fp.read())
+            self.assertIn(f"Deleted {migration_file}", out.getvalue())
+
+    def test_makemigrations_update_existing_name(self):
+        with self.temporary_migration_module(
+            module="migrations.test_auto_now_add"
+        ) as migration_dir:
+            migration_file = os.path.join(migration_dir, "0001_initial.py")
+            with open(migration_file) as fp:
+                initial_content = fp.read()
+
+            with captured_stdout() as out:
+                call_command("makemigrations", "migrations", update=True)
+            self.assertIs(os.path.exists(migration_file), False)
+            new_migration_file = os.path.join(
+                migration_dir,
+                "0001_initial_updated.py",
+            )
+            with open(new_migration_file) as fp:
+                self.assertNotEqual(initial_content, fp.read())
+            self.assertIn(f"Deleted {migration_file}", out.getvalue())
+
+    def test_makemigrations_update_applied_migration(self):
+        recorder = MigrationRecorder(connection)
+        recorder.record_applied("migrations", "0001_initial")
+        recorder.record_applied("migrations", "0002_second")
+        with self.temporary_migration_module(module="migrations.test_migrations"):
+            msg = "Cannot update applied migration 'migrations.0002_second'."
+            with self.assertRaisesMessage(CommandError, msg):
+                call_command("makemigrations", "migrations", update=True)
+
+    def test_makemigrations_update_no_migration(self):
+        with self.temporary_migration_module(module="migrations.test_migrations_empty"):
+            msg = "App migrations has no migration, cannot update last migration."
+            with self.assertRaisesMessage(CommandError, msg):
+                call_command("makemigrations", "migrations", update=True)
+
+    def test_makemigrations_update_squash_migration(self):
+        with self.temporary_migration_module(
+            module="migrations.test_migrations_squashed"
+        ):
+            msg = "Cannot update squash migration 'migrations.0001_squashed_0002'."
+            with self.assertRaisesMessage(CommandError, msg):
+                call_command("makemigrations", "migrations", update=True)
+
+    def test_makemigrations_update_manual_porting(self):
+        with self.temporary_migration_module(
+            module="migrations.test_migrations_plan"
+        ) as migration_dir:
+            with captured_stdout() as out:
+                call_command("makemigrations", "migrations", update=True)
+            # Previous migration exists.
+            previous_migration_file = os.path.join(migration_dir, "0005_fifth.py")
+            self.assertIs(os.path.exists(previous_migration_file), True)
+            # New updated migration exists.
+            files = [f for f in os.listdir(migration_dir) if f.startswith("0005_auto")]
+            updated_migration_file = os.path.join(migration_dir, files[0])
+            self.assertIs(os.path.exists(updated_migration_file), True)
+            self.assertIn(
+                f"Updated migration {updated_migration_file} requires manual porting.\n"
+                f"Previous migration {previous_migration_file} was kept and must be "
+                f"deleted after porting functions manually.",
+                out.getvalue(),
+            )
+
+    @override_settings(
+        INSTALLED_APPS=[
+            "migrations.migrations_test_apps.alter_fk.author_app",
+            "migrations.migrations_test_apps.alter_fk.book_app",
+        ]
+    )
+    def test_makemigrations_update_dependency_migration(self):
+        with self.temporary_migration_module(app_label="book_app"):
+            msg = (
+                "Cannot update migration 'book_app.0001_initial' that migrations "
+                "'author_app.0002_alter_id' depend on."
+            )
+            with self.assertRaisesMessage(CommandError, msg):
+                call_command("makemigrations", "book_app", update=True)
+
 
 class SquashMigrationsTests(MigrationTestBase):
     """