Our test suite runs on SQLite. Production runs on PostgreSQL. That is a common setup and for a long time it felt free: tests were fast, isolated, and green.
Over about three weeks we hit three separate bugs that all came from the same gap. None of them were caught by 1200+ passing tests, because the tests were running on an engine that quietly forgives what production rejects.
Here they are, in the order we found them.
1. Two tests that were red in production and green locally
We were making a schema change, so we ran the suite against a real Postgres instance for once. Two tests failed. On SQLite the same commit was 1241/1241 green.
