Deterministic ordering of records by created_at timestamp

Creating records in specs can be so fast that two records created instantly after one another might have the same created_at timestamp (especially since those timestamps don't have an indefinitely high resolution). When ordering lists by timestamps, you should therefore always include a final order condition using the primary key of the table.

Copyclass Photo < ActiveRecord::Base
  scope :by_date, -> { order('created_at DESC, id DESC') }
end

Photo.by_date

Remember to include the id field in the database index.