Test Data Engineering — Fixtures, Factories, and the Anonymization Trap
Every test runs against data, and at scale the data becomes its own engineering discipline: fixtures that encode last year's schema, factories that drift from what production actually produces, "anonymized" snapshots that are neither anonymous nor current, and demo environments whose data convinces no one. Test data rots faster than tests do — because nobody owns it — and the fix is the same as everywhere else in this series: make it declared, generated, versioned, and owned.
Test data engineered along a spectrum — exact fixtures for golden cases, real-path factories as the workhorse, statistics-driven synthesis for scale — with the anonymization trap named (quasi-identifiers re-identify, regulation follows the copy, snapshots rot anyway). Package it as versioned, owned, composable seed specs.