gistfile1.rb

require 'cancan/matchers'
require 'spec_helper'

describe Ability do

  describe Invoice do
    before(:each) do
      Invoice.any_instance.stub(:debit_fee_percent => 10)
      Invoice.any_instance.stub(:credit_fee_percent => 10)
    end
    it 'walker can create new invoice' do
      current_user = FactoryGirl.create :walker_with_invoice
      ability = Ability.new(current_user)
      ability.should be_able_to(:create, Invoice.new)
    end
    ...
    ...
end