The answer from Deltakosh provided you with the way we are testing the framework. This has changed, and I have pointed you to the way we test the framework now 
The babylon sourcecode is all out in the open. You can see exactly how we run tests and how they are integrated in our CI. The npm scripts can provide you with the jet commands required to get started.
It is not a trivial task, so it is not simple to explain, especially not in a forum post. I already gave you the abstract answer - jest, puppeteer and jest-screenshot for validation tests. The sourcecode is in our repository. There are two projects in tools you might find interesting, tests and testTools.
Having said that, I guess on our end we could provide a project that will run tests for you, based on that code. I am not sure how trivial this task is, but I will be happy to look into that in the future. You can create an issue on github, I will assign it to me.