Creating a simple Rails Engine despite the variety of documentation was confusing, so here is what I learned.
Source Code: https://github.com/marpori/rails_age RubyGem Link: https://rubygems.org/gems/rails_age AGE Demo App: https://github.com/marpori/rails_age_demo_app
It’s important to set up a dummy app from the beginning (to simplify testing)