RubyConf 2024 The Mutation Game: Cracking the Enigma of Mutation Testing by Tyler Lemburg

Can your application’s code achieve complete perfection? If you join Professor X’s School for Gifted Mutation Testers, it can get pretty dang close. Discover the Mystique of transforming your code in silly (and not-so-silly) ways, and seeing if this makes your tests fail. If your tests do fail, they are solid as a Colossus! If your tests passed, then you have discovered a Rogue mutant! But do not worry: I will teach you the ins and outs of squashing that mutant like a Blob and making your code stronger than Wolverine. Storm into this session and learn what mutation testing is all about, see if it may be right for your Ruby codebase, and explore the tools that make it possible. We will use the `mutant` gem and delve into an example Ruby app, bringing it to full mutation testing coverage through simplifying code and improving tests. Even if this technique is not right for your project, you will come away from this session with a deeper understanding of Ruby, code parsing, test-driven development, and writing clean, beautiful code.