7 posts
Mutation testing found a survivor and you have no idea what the mutation even does.
Your mutation testing report is full of survivors, and at least one of them makes no sense to you. The tool says it flipped a to a on line 47, or replaced an…
Why enforcing a single mutation score across your entire codebase is a mistake, and how to set per-module thresholds that match actual risk.
Enforcing a single mutation score across your entire codebase is a great way to make your team hate testing. Run PIT or Stryker against a typical repo and…
Code coverage says you're safe. Mutation testing says your tests are mostly decoration. Here's how surviving mutants expose the gap, and how to close it.
Your tests pass. Your coverage report says 87%. But your mutation score is 40%, and half your mutants are still alive. That 40% doesn't mean your code is…
cargo-mutants finds the tests that only pretend to verify your code.
You have 100% line coverage. Every branch is hit. Every function is called. Then someone changes a to a in your pricing logic, runs the tests, and they all…
Most teams don't run full mutation testing suites on every commit.
If your mutation testing suite takes four hours to run, congratulations. You've proven what everyone already suspected: your test suite has gaps. You are not…
If you want AI-generated code to survive production, do not rely on code review alone.
The most dangerous thing about AI-generated code is not that it is always wrong. It is that it is often good enough to merge. That is exactly what makes it…
Design by contract, property-based testing, mutation testing, and model checking were not bad ideas. They were too expertise-heavy to sustain.
Software engineering is full of ideas that look obviously correct the moment you read them. Of course contracts should define what a function is allowed to…