A kernel unit-testing framework

Posted Mar 9, 2019 1:14 UTC (Sat) by nix (subscriber, #2304)
In reply to: A kernel unit-testing framework by roc
Parent article: A kernel unit-testing framework

Spending double the development effort to have reasonable (not perfect) automated tests isn't outrageous. It's in the right ballpark for projects I've worked on like Firefox and rr. Under the right conditions that spend pays for itself pretty easily.

In glibc, which is very much following the 'everything should have tests dammit' policy (and long has), the tradeoff is sometimes much higher: it can easily take five times longer to write a decent test for some bugfixes than to fix the bug, even (sometimes especially!) when the bug is a real monster to find.

Linux would probably have terrible threading despite NPTL if Uli hadn't written a massive heap of tests for NPTL at the same time to make sure that the damn thing actually worked and did not regress. More than one bug I've looked at in the past which came down to one missed assembler instruction that triggered problems only in ludicrously obscure slowpath cases was tickled by one or more of those tests...