gistfile1.rb

## Factory

Factory.define :promo, :class => Promotion do |promo|
  promo.code                 "cm"
  promo.quantity             100
  promo.remaining            100
  promo.description         "for chris and mike"
end

## Spec

it "should decrement the promotion code's remaining value by one" do
  promo = Factory.create(:promo)
  get 'search', :q => 'flower -p cm'
  Promotion.find(promo.id).remaining.should == promo.remaining - 1
end

Here's how I would test it:

it "should decrement the promotion code's remaining value by one" do
 promo = Factory.create(:promo, :remaining => 2)
 get 'search', :q => 'flower -p cm'
 promo.reload.remaining.should == 1
end