DRY CanCan specs

cancan_rspec_dry.rb

    [
      [%w[c r u d], Widget],
    ].each do |tuple|
      permissions = tuple[0].map!(&:to_sym)
      model       = tuple[1]

      permissions.map! do |permission|
        case permission
        when :c then :create
        when :r then :read
        when :u then :update
        when :d then :delete
        end
      end

      permissions.each do |permission|
        it "can #{permission} #{model}" do
          if permission == :create
            should be_able_to(:create, model)
          else
            should be_able_to(permission, model.make!)
          end
        end
      end
    end