True enough, but ultimately the problem is some other code that did run and zigged instead of zagging to the code that didn't run. I tried to make that point point earlier ("may prompt useful questions about what logic led to them being skipped...").
Also a lesson in the usefulness of -skip. I've been pondering what a way to run an arbitrary selection of tests might look like. In this scenario, imagine running a specific set of tests and their inverse (modulo parent tests that must be run anyway). I'm not sure it's even possible currently.
Comments
"If you don't see the bug where you're looking, then you're looking in the wrong place."
https://onlinelibrary.wiley.com/doi/abs/10.1002/spe.4380060412
A nit: "code that didn’t run is not the problem". Not always. Maybe the bug is that it didn't run when it should have.
More broadly: the technique works much better if you have very good fine-grain testing, because the resolution of the diff is sharper.