Recently I’ve been refactoring legacy Test::Unit code to use shoulda. Sometimes you can’t factor out repetitive stuff into a context, but you still want to be DRY. Below is an example case of refactoring into a custom should. Note that you need to use class variables, and that the self.should_* method needs to be defined before it’s actually used, since shoulda is built upon metaprogramming which gets evaluated at the class level.

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  def self.should_request sym
    sym = sym.to_s
    context "when requesting #{sym}" do
      setup do
        get :download, {:id => @@podcast.id, :type => sym}, @@session
      end
      should "ask for a device" do
         assert_match /Please select a device to download content/,  @response.body
      end
      should "increment the message count when sent #add_to_device" do
        assert_difference 'Message.count( :conditions => "device_id = 1")', @@podcast.episodes.size do
          xhr :post, :add_to_device, {:id => 1, :type => 'all', :podcast_id => @@podcast.id}, @@session
        end
      end
    end
  end

  context "A valid account" do
    setup do
      @account = accounts(:accounts_002)
      @@session = {:account_id => @account.id}
      @account.devices << Device.find(1)
      @@podcast = podcasts(:joe_cartoon)
      @@session.merge!({:podcast_episodes => @@podcast.episodes})
    end

    should_request :all
    should_request :latest
    should_request :episode
  end

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