Added a (failing) test for when inflecting API

Author: Rob McFadzean

test/adapter_test.rb

@@ -38,6 +38,15 @@ def test_create_adapter_with_override
         adapter = ActiveModel::Serializer::Adapter.create(@serializer, { adapter: :json_api})
         assert_equal ActiveModel::Serializer::Adapter::JsonApi, adapter.class
       end
+
+      def test_inflected_adapter_class_for_known_adapter
+        ActiveSupport::Inflector.inflections(:en){|inflect| inflect.acronym 'API' }
+        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_api)
+
+        ActiveSupport::Inflector.inflections.acronyms.clear
+
+        assert_equal ActiveModel::Serializer::Adapter::JsonApi, klass
+      end
     end
   end
 end