request.rb

class Request < ActiveRecord::Base
  state_machine :state, :initial => :pending_owner_approval do
    event :approve do
      transition :from => :pending_owner_approval, :to => :pending_shipping_confirmation
    end
    
    event :deny do
      transition :from => :pending_owner_approval, :to => :denied
    end
    
    event :shipping_confirmed do
      transition :from => :pending_shipping_confirmation, :to => :in_transit
    end
    
    event :received do
      transition :from => :in_transit, :to => :complete
    end
  end
end

request_spec.rb

...
describe 'lifecycle' do
  it 'should start out as pending owner approval' do
    @model.should be_pending_owner_approval
  end
  
  it 'should be approved' do
    @model.approve
    @model.should be_pending_shipping_confirmation
  end
  
  it 'should be denied' do
    @model.deny
    @model.should be_denied
  end
  
  it 'should allow shipping to be confirmed' do
    @model.approve
    @model.shipping_confirmed
    @model.should be_in_transit
  end
  
  it 'should allow receipt of the item' do
    @model.approve
    @model.shipping_confirmed
    @model.received
    @model.should be_complete
  end
end