Grading the Grader: When Tests Fail to See

How good is your test suite really? Host A plants bugs while Host B watches tests pass anyway—some changes harmless, others cutting critical safety systems. They explore the mutation testing framework, kill rates, and the uncomfortable truth: a test suite that passes everything might be hiding catastrophic blind spots. 00:00 - Introduction: The bug-planting experiment 01:30 - First invisible bug: The harmless edit no test catches 05:00 - Second invisible bug: Removed backup interlock 08:00 - The paradox: Two invisible bugs, opposite meanings 10:00 - What is grading the grader? Mutation testing framework 12:00 - Episode 8 callback: The Compilation Illusion 14:00 - Kill rate scoring and the 90% benchmark --- Sources & further reading: • [peer-reviewed] Jia and Harman, *An Analysis and Survey of the Development of Mutation • Testing*, IEEE TSE 37(5):649–678, 2011, doi:10.1109/TSE.2010.62 — authors' copy • read 2026-09-24: http://crest.cs.ucl.ac.uk/fileadmin/crest/sebasepaper/JiaH10.pdf • (killed/survived definition, equivalent mutants, undecidability, mutation-score definition • quoted verbatim above). • [preprint] Evan Miller, *Adding Error Bars to Evals: A Statistical Approach to Language Model • Evaluations*, arXiv:2411.00640 — — checked 2026-09-24: https://arxiv.org/abs/2411.00640 • (quote and submission date). This podcast episode was fully generated by AI — research, script, voices, and production. Built with Claude, Piper TTS, and automated pipeline tooling.