## my validation code

 def validate_on_update
     puts("#{self.password} : #{User.obscure(old_password)}")
    if new_password and not new_password.empty? and User.obscure(old_password) != self.password
      puts 'adding error'
      errors.add(:password, "does not match old password")
    end
 end

 def after_validation_on_update
    self.password = User.obscure(self.new_password) if self.new_password and not self.new_password.empty?
    puts 'in after validation'
 end

## my test

it 'should not fail if the given old password is correct' do
  puts "starting update"
  User.update(1, {:new_password => 'frank',
                  :new_password_confirmation => 'frank',
                  :old_password => 'pass'}).should have(0).errors_on(:password)
end

## output from the test

"starting update"
"9d4e1e23bd5b727046a9e3b4b7db57bd8d6ee684 : 9d4e1e23bd5b727046a9e3b4b7db57bd8d6ee684"
"in after validation"
"86a8c2da8527a1c6978bdca6d7986fe14ae147fe : 9d4e1e23bd5b727046a9e3b4b7db57bd8d6ee684"
"adding an error"
"in after validation"


## in console

>> User.update(2, {:new_password => 'frank', :new_password_confirmation => 'frank', :old_password => 'test'})
a94a8fe5ccb19ba61c4c0873d391e987982fbbd3 : a94a8fe5ccb19ba61c4c0873d391e987982fbbd3
in after validation
=> #<User:0xb72da854 @new_password_confirmation="frank", @new_record_before_save=nil, @errors=#<ActiveRecord::Errors:0xb72d9d00 @errors={}, @base=#<Rider:0xb72da854 ...>>, @old_password="test", @new_password="frank", @attributes={"name"=>"evan", "id"=>"2", "password"=>"86a8c2da8527a1c6978bdca6d7986fe14ae147fe", "email"=>"evan"}>