Rails 3 Email Validator

email_validator.rb

require 'mail'

class EmailValidator < ActiveModel::EachValidator
  attr_reader :record, :attribute, :value, :email, :tree

  def validate_each(record, attribute, value)
    @record, @attribute, @value = record, attribute, value

    @email = Mail::Address.new(value)
    @tree  = email.__send__(:tree)

    add_error unless valid?
  rescue Mail::Field::ParseError
    add_error
  end

  private

  def valid?
    !!(domain_and_address_present? && domain_has_more_than_one_atom?)
  end

  def domain_and_address_present?
    email.domain && email.address == value
  end

  def domain_has_more_than_one_atom?
    tree.domain.dot_atom_text.elements.length > 1
  end

  def add_error
    if message = options[:message]
      record.errors[attribute] << message
    else
      record.errors.add(attribute, :invalid)
    end
  end
end

email_validator_spec.rb

require 'spec_helper'

VALID_RECOMMENDATION_ATTRS = {
  :first_name => "John",
  :recipient_email => "[email protected]"
}

describe EmailValidator do
  subject { Recommendation.make_unsaved(VALID_RECOMMENDATION_ATTRS) } # assumes Machinist

  %w[[email protected] [email protected] [email protected] [email protected]].each do |good_email|
    it { should allow_value(good_email).for(:recipient_email) }                 # assumes shoulda-matchers
  end
  (%w[haxors @blah can@haz] + ['[email protected], [email protected]']).each do |bad_email|
    it { should_not allow_value(bad_email).for(:recipient_email) }
  end
end