I mean, from my training long ago, a good test suite is usually / always a few multiples in size of the codebase.
100k lines of app code? 300-500k lines of test, sort of thing.
100k lines of app code? 300-500k lines of test, sort of thing.
I am now looking at 9 to 10x the app code, for non trivial stuff. And this is not just the usual unit/integration/e2e suites too. Extensive deadcode, field use, code shape tests (ast walking) - god objects, 15-param helpers, wrapper-piled-upon-wrapper, badly named (a skill) functions/methods/objects, path-dependent artifacts, etc. There is no way I could have written all this manually.
It doesn't guarentee high quality OR reliability or readability or maintainability, but does reduce churn and makes me feel a bit more confident about deploying route A work product in prod.