TestUnit - Writing Test Code In Ruby (1/3)

I'm training my juniors on how to write test code since we need to improve our code coverage in ExamPro. I had quickly put together three guides last Sunday on TestUnit, MiniTest and RSpec. Why all three? I believe that learning by variation results in complete knowledge.I figured I should publish these three articles on DEV.to articles "as is" otherwise I'll forget about them, they'll end up in my "Dump" folder, never to been seen again.p.s. I had written challenges to each of these guides. I don't know if people want them. Show me enough reactions, comment below if you want them, and I'll find the time to publish them if there's interest.