The Mutation Game: Cracking the Enigma of Mutation Testing
summary
Uses the mutant gem (backed by the parser gem) to mutate Ruby ASTs, run RSpec against each variant, and report concrete failures; the live Benedict versus X‑Men demo shows debugging fixes like replacing [] with fetch, == with equal, removing stray puts and unnecessary to_f, and hitting 20 mutations with 18 killed before adding tests and simplifying code to reach 100% for methods. Notes: slow in CI, problematic on large Rails apps, cannot mutate methods inside eval/closures, $90/seat commercial license.
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chapters (9)
- 0:00Mutation testing intro
- 1:50What mutation testing does
- 3:55Common mutation patterns
- 4:58Ruby mutation tools
- 6:21Live demo: Benedict vs X-Men
- 17:50Mutation testing benefits
- 19:55Limitations of mutation testing
- 21:38Use mutation testing?
- 24:46Q&A
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