macros.rb

module RailsBestPractices
  module Macros

    def self.included(base)
      # Calling of "include RailsBestPractices::Macros" will make all macros available as
      # class methods within describe { ... }
      base.extend(ClassMethods)
    end

    module ClassMethods

      def should_be_user_ownable(factory_id = nil)

        # default_factory_id (see below) should be able to derive a sensible one, but may
        # be exception (a little over-engineered, but a simple one)
        factory_id ||= default_factory_id

        # generates an example group
        describe 'being user ownable' do

          # The rest are just relocated from original spec, with the replacing of hardcoded
          # factory name with factory_id

          should_belong_to :user

          it 'should belong to someone if he is the owner of it' do
            someone = Factory(:user)
            Factory(factory_id, :user => someone).belongs_to?(someone).should be_true
          end

          it 'should not belong to someone if he is not the owner of it' do
            someone = Factory(:user)
            Factory(factory_id).belongs_to?(someone).should be_false
          end

        end
      end

      private

        def default_factory_id
          # derive a factory name, based on the current context class
          context_klass.to_s.tableize.singularize.to_sym
        end

        def context_klass
          # NOTE: This part is abit brittle, assumes the the context description to be a
          # stringified class name or the class itself, Eg:
          # 
          # Works for:
          # - describe Customer::PurchaseOrder { ... }
          # - describe 'Customer::PurchaseOrder' { ... }
          # 
          # BUT not for:
          # - describe 'Customer Purchase Order' { ... }
          #
          self.description.split('::').inject(Object) {|klass, const| klass.const_get(const) }
        end

    end
  end
end