gistfile1.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

require "nokogiri"

class HTMLTransformer
  
  def initialize(xpath, &block)
    @xpath = xpath
    @block = block
  end
  
  def transform(html)
    doc = Nokogiri::HTML(html)
    body = doc.at("/html/body")
    
    body.xpath(@xpath).each do |node|
      @block.call(node)
    end
    
    body.inner_html
  end
  
end

class PrivateProfileLinkDecorator
  
  def self.decorate(html)
    transformer = HTMLTransformer.new(xpath) do |node|
      add_rel_attribute(node)
    end
    transformer.transform(html)
  end
  
  def self.add_rel_attribute(node)
    node.set_attribute("rel", "jsfacebox.private_profile_dialog")
  end
  
  def self.xpath
    "//a[contains(@class, 'user_link')]"
  end
  
end

describe PrivateProfileLinkDecorator do
  
  it "should not modify non-links" do
    html = "<p>Hi</p>"
    PrivateProfileLinkDecorator.decorate(html).should == html
  end

  it "should not modify links without the user_link class" do
    html = "<a>link</a>"
    PrivateProfileLinkDecorator.decorate(html).should == html
  end
  
  it "should modify links" do
    html = "<a class='user_link'>link</a>"
    PrivateProfileLinkDecorator.decorate(html).should ==
      "<a class=\"user_link\" rel=\"jsfacebox.private_profile_dialog\">link</a>"
  end
  
end