Classes are Open

David Heinemeier Hansson:

• I require the original payment gateway first, then I re-open the class and mock out the behavior that I want to change. In this case, its the commit method that would otherwise start to talk to the Authorize.net server.

require 'models/payment_gateway'

class PaymentGateway
  def commit
    SuccessfullSubmission.new
  end
end