https://chrisherring.co/posts/testing-a-feature-with-rails-and-rspec-a-deep-dive
https://code.tutsplus.com/tutorials/testing-your-ruby-code-with-guard-rspec-pry-part-2--cms-20290
http://cheatrags.com/rspec-matchers
https://code.tutsplus.com/articles/rspec-testing-for-beginners-03--cms-26728
https://code.tutsplus.com/articles/rspec-testing-for-beginners-02--cms-26720
https://code.tutsplus.com/articles/rspec-testing-for-beginners-part-1--cms-26716
http://shiroyasha.io/sinatra-app-with-rspec.html
https://cucumber.io/