Refs #29506 -- Added validation for squashmigrations' app_label option.

django/core/management/commands/squashmigrations.py

@@ -1,3 +1,4 @@
+from django.apps import apps
 from django.conf import settings
 from django.core.management.base import BaseCommand, CommandError
 from django.db import DEFAULT_DB_ALIAS, connections, migrations
@@ -46,7 +47,11 @@ class Command(BaseCommand):
         migration_name = options['migration_name']
         no_optimize = options['no_optimize']
         squashed_name = options['squashed_name']
-
+        # Validate app_label.
+        try:
+            apps.get_app_config(app_label)
+        except LookupError as err:
+            raise CommandError(str(err))
         # Load the current graph state, check the app and migration they asked for exists
         loader = MigrationLoader(connections[DEFAULT_DB_ALIAS])
         if app_label not in loader.migrated_apps:

tests/migrations/test_commands.py

@@ -1433,3 +1433,11 @@ class AppLabelErrorTests(TestCase):
     def test_migrate_app_name_specified_as_label(self):
         with self.assertRaisesMessage(CommandError, self.did_you_mean_auth_error):
             call_command('migrate', 'django.contrib.auth')
+
+    def test_squashmigrations_nonexistent_app_label(self):
+        with self.assertRaisesMessage(CommandError, self.nonexistent_app_error):
+            call_command('squashmigrations', 'nonexistent_app', '0002')
+
+    def test_squashmigrations_app_name_specified_as_label(self):
+        with self.assertRaisesMessage(CommandError, self.did_you_mean_auth_error):
+            call_command('squashmigrations', 'django.contrib.auth', '0002')