A fast and robust way to run Sauce Labs tests in Circle CI

We've been using Circle CI at Appuri for many months now and have been very happy with it. It's very simple and has a great breadth of features, namely the ability to SSH into a build to diagnose it when things get really tricky, as well as docker build services, slack integration, and lots of built-in services. After I hit a wall with PhantomJS, and needing to run our tests on multiple browsers anyways, it was time to integrate Sauce Labs to do our browser testing, which I've had great experience with on many open source projects. In those projects I used grunt-saucelabs as I am not a big fan of Karma as I like to control the HTML page the tests run on as well as the simplicity of mocha-phantomjs and just refreshing a flat file or using browser sync.

However we're using gulp and I didn't want to pull in grunt and have two build systems. Unfortunately there's no gulp-saucelabs, which I contemplated doing (I may sometime), but I found I could simply use mocha-cloud. However, it didn't bring up the tunnel.