# Testing & QA > Selected Engineer ApS work demonstrating Testing & QA — the achievements that prove it. - [Kept the schema honest across 1,022 migrations with a CI gate that builds the database both ways — a fresh install, and an install plus every migration — and fails when the two disagree.](https://data.engineer.company/portfolio/kept-the-schema-honest-across-1022-migrations-99/) - [Wrote tests for the checkers themselves after establishing that a checker fed only clean input will one day report clean because it read nothing — planting a misspelling to confirm the spell‑check finds it, and taking an id range from the database rather than from a number in the test.](https://data.engineer.company/portfolio/wrote-tests-for-the-checkers-themselves-149/) - [Built a cross‑language content check that fails when a translation drops a figure the English states, and when a language uses notation it does not use — finding two Danish descriptions missing a metric and sixteen Ukrainian spans quoting in the English style.](https://data.engineer.company/portfolio/built-a-cross-language-figure-and-notation-check-153/)