An attempt to outline getting headless testing up and in running as quick, easy, and effectively in today's ever-modernizing landscape.
As of right now I am doing a Landscape Review and will try to choose ONE set of tools and methods to write up. I'm currently leaning toward Ghost Inspector w/ Selenium.
https://ghostinspector.com/docs/selenium-import-export/
I'll try to set up a demo with Selenium Builder soonish probably never.
Selenium IDE Firefox add-on end of life
Puppeteer - Puppeteer is a Node library which provides a high-level API to control headless Chrome over the DevTools Protocol. It can also be configured to use full (non-headless) Chrome.
CasperJS - CasperJS is a browser navigation scripting & testing utility written in Javascript for PhantomJS or SlimerJS.
Ghost Inspecter - Painlessly Record Tests in Your Browser