title: Listening to a polymer attached event from outside that element
body: <p>In my team we are trying to write some unit tests for polymer custom elements. Most of our custom elements uses Polymer's template binding feature so we have lots of code written under attached callback of a custom element.
  When writing unit tests for these elements I can only listen to polymer-ready event but what we need is to run our test suite only after the polymer-attached event so the binding has already been complete.</p>
  
  <p>Right now we have done a dirty checking for the element we want to check so that our test suite only runs after the complete template gets bounded.</p>
  
  <p><strong>I have already seen a <a href="https://stackoverflow.com/questions/21763690/polymer-and-webcomponentsready-event">post</a> where Polymer exposes a way to listen to ready event but what we need is a way to listen to polymer's attached event from outside polymer.</strong></p>