Evaluate association blocks as scopes on the association

test/serializers/associations_test.rb

@@ -128,8 +128,8 @@ module ActiveModel
 
       class InlineAssociationTestPostSerializer < ActiveModel::Serializer
         has_many :comments
-        has_many :last_comments do
-          object.comments.last(1)
+        has_many :comments, key: :last_comments do
+          last(1)
         end
       end