Learn RSpec

[Czarrrna]

• [x] https://semaphoreci.com/community/tutorials/getting-started-with-rspec
• [x] http://rspec.info/
• [x] https://relishapp.com/rspec/rspec-rails/v/3-3/docs/model-specs
• [x] http://everydayrails.com/2012/03/12/testing-series-intro.html
• [x] https://robots.thoughtbot.com/how-we-test-rails-applications
• [x] http://betterspecs.org/

[Czarrrna]

• [x] make a tutorial about testing
• [ ] add some tests to CalculatorApp