Is there a way to use a command line tool to view the JavaScript interpreted source of a web page?
Have you looked in to tools like PhantomJS for running the tests? Many of them support running a "headless" browser, which lets you render pages and run JS against the rendered page without having to actually run a browser. It doesn't use curl, but I don't see why that should be a requirement.
For instance:
$ phantomjs save_page.js http://example.com with save_page.js:
var system = require('system');var page = require('webpage').create();page.open(system.args[1], function(){ console.log(page.content); phantom.exit();});