<app-shell>
Install the Polymer-CLI
First, make sure you have the Polymer CLI and npm (packaged with Node.js) installed. Run npm install to install your element's dependencies, then run polymer serve to serve your element locally.
Viewing Your Element
$ polymer serve
Running Tests
$ polymer test
Your application is already set up to be tested via web-component-tester. Run polymer test to run your application's test suite locally.