Automation Test Toolkit in NAV 2016

I would like to test my customization around the purchase flow in a Cronus demo database using Automation Test ToolKit. It's a simple customization and i would like to test it, that it shouldn't break the normal purchase flow. There are so much of Libraries been provided by microsoft and it's tedious for me to pick the exact library. So please give me some suggestion, as there are only few articles are available around this area.