Rails Validations not running when I use :on => :save option

Rails validations not running

This gist is in reference to the documentation for the Rails 3.2.13 on Ruby 1.9.3 p194 (http://guides.rubyonrails.org/active_record_validations_callbacks.html#on) where it has highlighted the fact that the validations for presence can also be run using the :on => :save option. The following code will highlight it better

class User < ActiveRecord::Base
  attr_accessible :name
  validates :name, :presence => true, :on => :save
end

u = User.create
u.errors #=> nil

u = User.first
u.name = ""
u.save #=> nil

The presence validation for name has not fired which is contradictory to what is stated in the above guide.