class PersonTest < ActiveSupport::TestCase
  should_validate_email_format_of :email
end

class Person < ActiveRecord::Base
  validates_email_format_of :email
end

:message =>
  String. A custom error message (default is: " does not appear to be a valid e-mail address")

:on =>
  Symbol. Specifies when this validation is active (default is :save, other options :create, :update)

:allow_nil =>
  Boolean. Allow nil values (default is false)

:allow_blank =>
  Boolean. Allow blank values (default is false)

:if =>
  Specifies a method, proc or string to call to determine if the validation should occur 
  (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, 
  proc or string should return or evaluate to a true or false value. 

:unless =>
  See :if option.