Migration Testing
Migration testing verifies that data and functionality transfer correctly when moving from one system, platform, or database to another — checking that no data is lost, corrupted, or misinterpreted, and that the migrated system behaves the same as the original once the migration completes.
Migrations are high-risk precisely because they typically happen once, on production data, with limited ability to "just try again" if something goes wrong — a bad migration can mean real data loss, not just a bug to fix in the next release.
Solid migration testing runs against a full copy of production-like data (not a small sample), verifies record counts and checksums before and after, spot-checks data integrity on a sample of records, and tests the rollback plan just as thoroughly as the forward migration — because the rollback is what gets used under pressure if something breaks mid-migration.
