diff --git a/test/fixtures/active_record.rb b/test/fixtures/active_record.rb
index <HASH>..<HASH> 100644
--- a/test/fixtures/active_record.rb
+++ b/test/fixtures/active_record.rb
@@ -963,9 +963,9 @@ class PostResource < JSONAPI::Resource
   end
 
   def self.sortable_fields(context)
-    super(context) - [:id]
+    super(context) - [:id] + [:"author.name"]
   end
-
+ 
   def self.verify_key(key, context = nil)
     super(key)
     raise JSONAPI::Exceptions::RecordNotFound.new(key) unless find_by_key(key, context: context)
diff --git a/test/test_helper.rb b/test/test_helper.rb
index <HASH>..<HASH> 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -116,14 +116,6 @@ module Pets
   end
 end
 
-class PostResource < JSONAPI::Resource
-  attribute :id
-
-  def self.sortable_fields(context)
-    (super(context) << :"author.name") - [:id]
-  end
-end
-
 JSONAPI.configuration.route_format = :underscored_route
 TestApp.routes.draw do
   jsonapi_resources :people
Add relationship sortable field to PostResource and take out of TestHelper