def code_used?
  errors.add(:code, "Code used") if used
  used
end

def find_promotional_code(params)
  PromotionalCode.find_by(code: params[:code])
end

require 'rails_helper'

RSpec.describe PromotionalCode, :type => :model do
  describe '.promotional_code' do
    promotional_code = FactoryGirl.create(:promotional_code)

    context 'code used' do
      result = promotional_code.used?
      it { expect(result).to be(false) }
    end
  end
end

def payment_with_promotional_code
  if find_promotional_code
    find_promotional_code.update_attributes(used: true) if current_user.set_payment
    redirect_to  properties_path
  elsif find_promotional_code.nil?
    redirect_to new_property_path, alert: "Please make sure you have a valid code"
  else
    redirect_to new_property_path, alert: "Please make sure you have a valid code"
  end
end

require 'rails_helper'

RSpec.describe ChargesController, :type => :controller do

  describe "payment with promotional code" do
    promotional_code = FactoryGirl.create(:promotional_code)

    context "promotional code valid" do
      result = promotional_code.find_promotional_code(code: "M18A")
      it { expect(result).not_to be_nil } 
      it { expect {promotional_code.update(used: true)}}
    end

    context "promotional code not valid" do
      result = promotional_code.find_promotional_code(code: "H75")
      it { result.should be_nil }
    end

    context "promotional code nil" do
      it { expect(promotional_code.code).not_to be_empty }
    end
  end
end