Explore mutation testing fundamentals in this 25-minute conference talk from RubyConf 2024 that uses X-Men-themed analogies to demonstrate how deliberately introducing code changes can validate test effectiveness. Learn to leverage the `mutant` gem to identify weak test coverage, analyze code parsing techniques, and implement test-driven development practices through a hands-on Ruby application example. Master the process of detecting and eliminating problematic mutations while gaining deeper insights into writing clean, maintainable Ruby code. Whether implementing mutation testing in production or seeking to enhance general coding practices, gain valuable knowledge about code quality assessment, test coverage improvement, and Ruby development best practices.