Added test case for association propagating options

test/fixtures/poro.rb

@@ -113,6 +113,13 @@ end
 class PostSerializer < ActiveModel::Serializer
   attributes :title, :body
 
+  def title
+    keyword = serialization_options[:highlight_keyword]
+    title = object.read_attribute_for_serialization(:title)
+    title = title.gsub(keyword,"'#{keyword}'") if keyword
+    title
+  end
+
   has_many :comments
 end