Lorem ipsum doesn't ship products

Typing "asdf" into a ZIP field tells you the validator rejects garbage — which you already knew. What it does not tell you is whether the address pipeline downstream can handle a real record: geocoding, tax lookup, fraud scoring, fulfillment routing.

Format-aware test data passes the gate on purpose, so it reaches the layers where genuine bugs live.

The three failure classes

Realistic sample data cleanly separates three failure classes: rejection (validation catches it — expected), acceptance with wrong downstream behavior (a real bug), and acceptance with correct behavior (the happy path). Pure garbage input merges all three into one undifferentiated pile of errors.

Making it a habit

Keep a generator tab open next to your test runner. Pull a fresh batch of records per session, save the interesting ones, and export them into fixtures. Reproducible, plausible input is the cheapest test infrastructure you will ever set up.