Fix create_perm in apps.py to use database alias given by the post_migrate signal

constance/apps.py

@@ -12,7 +12,7 @@ class ConstanceConfig(AppConfig):
         signals.post_migrate.connect(self.create_perm,
                                      dispatch_uid='constance.create_perm')
 
-    def create_perm(self, *args, **kwargs):
+    def create_perm(self, using=None, *args, **kwargs):
         """
         Creates a fake content type and permission
         to be able to check for permissions
@@ -21,12 +21,12 @@ class ConstanceConfig(AppConfig):
         from django.contrib.contenttypes.models import ContentType
 
         if ContentType._meta.installed and Permission._meta.installed:
-            content_type, created = ContentType.objects.get_or_create(
+            content_type, created = ContentType.objects.using(using).get_or_create(
                 app_label='constance',
                 model='config',
             )
 
-            permission, created = Permission.objects.get_or_create(
+            permission, created = Permission.objects.using(using).get_or_create(
                 name='Can change config',
                 content_type=content_type,
                 codename='change_config')

tests/settings.py

@@ -23,6 +23,10 @@ DATABASES = {
     'default': {
         'ENGINE': 'django.db.backends.sqlite3',
         'NAME': ':memory:',
+    },
+    'secondary': {
+        'ENGINE': 'django.db.backends.sqlite3',
+        'NAME': ':memory:',
     }
 }
 

tests/test_app.py

@@ -0,0 +1,46 @@
+from django.apps import apps
+from django.contrib.auth.models import Permission
+from django.contrib.contenttypes.models import ContentType
+from django.db.models import signals
+from django.test import TestCase
+
+
+class TestApp(TestCase):
+    def setUp(self):
+        self.app_config = apps.get_app_config('constance')
+
+    def test_post_migrate_signal_creates_content_type_and_permission_in_default_database(self):
+        self.assert_uses_correct_database('default')
+
+    def test_post_migrate_signal_creates_content_type_and_permission_in_secondary_database(self):
+        self.assert_uses_correct_database('secondary')
+
+    def test_uses_default_db_even_without_giving_using_keyword(self):
+        self.call_post_migrate(None)
+
+        self.assert_content_type_and_permission_created('default')
+
+    def assert_uses_correct_database(self, database_name):
+        self.call_post_migrate(database_name)
+
+        self.assert_content_type_and_permission_created(database_name)
+
+    def assert_content_type_and_permission_created(self, database_name):
+        content_type_queryset = ContentType.objects.filter(app_label=self.app_config.name) \
+            .using(database_name)
+
+        self.assertTrue(content_type_queryset.exists())
+
+        permission_queryset = Permission.objects.filter(content_type=content_type_queryset.get()) \
+            .using(database_name).exists()
+
+        self.assertTrue(permission_queryset)
+
+    def call_post_migrate(self, database_name):
+        signals.post_migrate.send(
+            sender=self.app_config,
+            app_config=self.app_config,
+            verbosity=None,
+            interactive=None,
+            using=database_name
+        )