This is so needed for WooCommerce. I cannot tell you how many store owners I know or have worked with have dealt with this pain point and, more times than not, didn't know their cart wasn't working till some customer sent them a note or a public Tweet. Then all you wonder is how many you lost that didn't let you know. Great job!
Robot Ninja couldn't be easier to use – just link up your store to run a test right away, or schedule automated tests to run in the background whenever you want. Definitely one to sign up for if you stress a lot about whether your checkout is actually working properly!