testing – Page 16 – Türker Yıldırım

A multi-stage target that exists only to run tests

NoteNovember 15, 20222 min read

A named stage installing dev dependencies and running the suite guarantees the test environment is the runtime environment plus tools, rather than a second description that drifts. Stages…

A queue worker that scales on the metric that matters

Deep diveNovember 9, 202210 min read

Six workers, always, whether there is work or not. A backlog at 09:00 and idle capacity at 03:00.

An idempotent consumer for a broker that redelivers

Deep diveNovember 8, 202210 min read

A message processed twice, and a customer charged twice. At-least-once delivery, treated as exactly-once by the handler.

Two teams, one database, and the schema change that needed a meeting

Deep diveOctober 29, 202210 min read

A shared schema, and a rename that took three weeks to coordinate. Table ownership that exists in nobody’s head.

tmpfs for a test database, and the flush settings that matter

NoteOctober 21, 20222 min read

A test database is disposable, so paying for durability is paying for a guarantee about data that is deleted at the end of the run. Most of the…

Coverage of a line is not coverage of a branch

NoteOctober 20, 20222 min read

Line coverage counts whether a line executed, and a line with two outcomes is fully covered by exercising one of them. Path coverage requires Xdebug rather than PCOV…

A cache invalidation bug that only appeared under load

Deep diveOctober 17, 202210 min read

Correct in every test, wrong for about one request in four thousand. A read that races a write, and a cache that keeps the loser.

A path filter and the required check that never runs

NoteOctober 13, 20222 min read

A workflow with a path filter does not run when nothing matched, and a required status check that never runs blocks the pull request forever. The duplicate-workflow trick…

docker compose –profile, and the nine services you rarely need

NoteOctober 10, 20222 min read

A service with no profile always starts, which makes the default stack minimal and everything else opt-in — the right way round, and the opposite of how these…

A monorepo for four packages and one application

Deep diveOctober 5, 202210 min read

Four packages, four repositories, and a change that spans three. A version bump dance that takes an afternoon.