Avoid running migration check multiple times in tests

Author: AlanCoding

test_app/tests/conftest.py

@@ -44,12 +44,14 @@ def openapi_schema():
     return generator.get_schema(request=drf_request)
 
 
-def test_migrations_okay(*args, **kwargs):
+def test_migrations_okay(apps, app_config, **kwargs):
     """This test is not about the code, but for verifying your own state.
 
     If you are not migrated to the correct state, this may hopefully alert you.
     This is targeted toward situations like switching branches.
     """
+    if app_config.label != 'test_app':
+        return  # so that it is only ran once
     disk_steps = defaultdict(set)
     app_exceptions = {'default': 'auth', 'social_auth': 'social_django'}
     for app in MigrationRecorder.Migration.objects.values_list('app', flat=True).distinct():
@@ -60,6 +62,9 @@ def test_migrations_okay(*args, **kwargs):
         except LookupError:
             raise RuntimeError(f'App {app} is present in the recorded migrations but not installed, perhaps you need --create-db?')
 
+        if (not hasattr(app_config, 'module')) or (not hasattr(app_config.module, 'migrations')):
+            continue  # might catch a stub app
+
         migration_module = app_config.module.migrations
         for step in dir(migration_module):
             if not re.match(r'\d{4}_', step):