light.rb

# Make this code more readable or remove duplication... or both!

require 'micromachine'
self.class.const_set(:Event, Class.new)
self.class.const_get(:Event).class_eval do

  def method_missing(method_sym, *arguments, &block)
    case method_sym
    when :confirm!, :cancel!, :reset!
      confirmation.method(:trigger)[method_sym.to_s.gsub('!','').to_sym]
    when :confirmation_state
      confirmation.send("state")
    when :confirmation
      @confirmation ||= MicroMachine.new(@confirmation_state || "pending").tap do |fsm|
                          fsm.when(:confirm, "pending" => "confirmed")
                          fsm.when(:cancel, "confirmed" => "cancelled")
                          fsm.when(:reset, "confirmed" => "pending", "cancelled" => "pending")
                        end
    end
  end
end

require 'minitest/autorun'

describe Event do
  let(:event){ Event.new }

  it "begins as pending" do
    _(event.confirmation_state).must_equal "pending"
  end

  it "transitions from pending to confirmed" do
    event.confirm!
    _(event.confirmation_state).must_equal "confirmed"
  end

  it "transitions from confirmed to cancelled" do
    event.confirm!
    _(event.confirmation_state).must_equal "confirmed"
    event.cancel!
    _(event.confirmation_state).must_equal "cancelled"
  end

  it "transitions from confirmed to pending" do
    event.confirm!
    _(event.confirmation_state).must_equal "confirmed"
    event.reset!
    _(event.confirmation_state).must_equal "pending"
  end

  it "transitions from cancelled to pending" do
    event.confirm!
    event.cancel!
    _(event.confirmation_state).must_equal "cancelled"
    event.reset!
    _(event.confirmation_state).must_equal "pending"
  end

  it "remains pending if cancelled" do
    event.cancel!
    _(event.confirmation_state).must_equal "pending"
  end
end