Resolve groups for owner

Group owner does not necessary (= by default) have the core.view_group permission, but should be able to view his groups anyway.

This is needed for courses_of_teacher to return the groups of the course as well.

aleksis/apps/cursus/schema.py

@@ -144,7 +144,11 @@ class CourseType(PermissionsTypeMixin, DjangoFilterMixin, DjangoObjectType):
 
     @staticmethod
     def resolve_groups(root, info, **kwargs):
-        return get_objects_for_user(info.context.user, "core.view_group", root.groups.all())
+        by_permission = get_objects_for_user(
+            info.context.user, "core.view_group", root.groups.all()
+        )
+        by_ownership = info.context.user.person.owner_of.all() & root.groups.all()
+        return by_permission | by_ownership
 
     @staticmethod
     def resolve_course_id(root, info, **kwargs):