gistfile1.rb

require 'rubygems'
require 'activerecord'

$:.unshift('lib')
require 'state_machine'

ActiveRecord::Base.establish_connection({
  :adapter => 'mysql',
  :database => 'test',
  :username => 'root'
})

ActiveRecord::Base.connection.execute "DROP TABLE IF EXISTS foos"
ActiveRecord::Base.connection.execute <<EOSQL
  CREATE TABLE foos (
   id INT NOT NULL AUTO_INCREMENT,
   state VARCHAR(255),
   string VARCHAR(255),
   PRIMARY KEY (id)
  );
EOSQL

class Foo < ActiveRecord::Base
  attr_reader :changes_before_update, :changes_before_save

  state_machine :initial => 'park' do
    event :ignite do
      transition :park => :idling
    end

    event :park do
      transition :idling => :park
    end
  end

  def before_save
    @changes_before_save = changes
  end

  def before_update
    @changes_before_update = changes
  end
end

require 'test/unit'

class AttributeTest < Test::Unit::TestCase
  def setup
    Foo.delete_all
  end

  def test_initial
    foo = Foo.new( :string => 'arb' )
    foo.save

    expected = { 'state' => [ nil, 'park' ], 'string' => [ nil, 'arb' ] }
    assert_equal expected, foo.changes_before_save
  end

  def test_changes
    foo = Foo.new
    foo.save

    foo.update_attribute :string, 'arb'
    expected = { "string" => [ nil, "arb" ] }
    assert_equal expected, foo.changes_before_update

    foo.ignite!

    expected = { "state" => [ 'park', 'idling' ] }
    assert_equal expected, foo.changes_before_update
  end
end