gistfile1.rb

# -*- mode: ruby; coding: utf-8-unix -*-

require 'active_model'

class User
  include ActiveModel::Validations

  attr_accessor :email
  attr_accessor :password

  attr_reader :password_check_mode

  validates :email, :presence => true, :unless => :password_check_mode
  validates :password, :presence => true

  def password_check
    @password_check_mode = true
    valid?
  ensure
    @password_check_mode = false
  end
end

u1 = User.new
u1.password = 'passw0rd'

raise if u1.valid?

u2 = User.new
u2.password = 'passw0rd'

raise unless u2.password_check