Every backend that touches a date of birth ends up reinventing the same arithmetic. I've watched it happen in three codebases this year alone: a fintech KYC service, a healthcare intake portal, and a small HR tool for a startup. The bug shape is almost always identical — somebody computes age b...
Source: [Dev.to](https://dev.to/lizely/stop-reinventing-the-wheel-a-qa-pattern-for-date-math-in-user-facing-code-4kb7)