Honestly, I feel confused when I was first learning the topic “testing in isolation”. I always struggle these questions: “What Stubs, Mocks and Spies means?”, “What purpose of using these techniques?”, “Which techniques should we use to apply certain scenarios?”. In this simple guide, let try to demystify these techniques by using the concrete examples.

https://designcode.commandrun.com/testing-rails-simple-guide-part-3-9ed5355f6aea