Ensure JSON serializer includes model naming

activemodel/lib/active_model/serializers/json.rb

@@ -10,6 +10,8 @@ module JSON
       include ActiveModel::Attributes
 
       included do
+        extend ActiveModel::Naming
+
         cattr_accessor :include_root_in_json, :instance_writer => false
       end
 

activemodel/test/cases/json_serialization_test.rb

@@ -2,7 +2,6 @@
 
 class JsonSerializationTest < ActiveModel::TestCase
   class Contact
-    extend ActiveModel::Naming
     include ActiveModel::Serializers::JSON
     attr_accessor :name, :age, :created_at, :awesome, :preferences
   end