gistfile1.rb

  let(:address_model) do
    Class.new do
      include ActiveModel
      include ActiveModel::Validations
      include HasAddress

      def initialize(attributes = {}) 
        @attributes = attributes
      end 

      def [](attr)
        @attributes[attr]
      end 

      def []=(attr, value)
        @attributes[attr] = value
      end 
    end 
  end