Stories, insights, and opinions from the team behind Mergifyhttps://mergify.com/https://mergify.com/blog/pytest-xdist-ordering-races/mergify-blog:pytest-xdist-ordering-racesWhy a test that always passes alone fails on `pytest -n auto`, the fixture-scope rule that prevents most worker races, and the worker_id pattern for genuinely shared resources.Sat, 09 May 2026 00:00:00 GMTtestingnoreply@mergify.com (Rémy Duthu)https://mergify.com/blog/rspec-order-dependent-specs-random-seed/mergify-blog:rspec-order-dependent-specs-random-seedWhy a green spec on `--order defined` fails on `--order random` with a different seed every CI run, how to bisect to the dependent pair, and the cleanup hooks that fix the underlying coupling.Thu, 07 May 2026 00:00:00 GMTtestingnoreply@mergify.com (Rémy Duthu)https://mergify.com/blog/new-hire-on-a-codebase-i-didnt-write/mergify-blog:new-hire-on-a-codebase-i-didnt-writeA new engineer at Mergify built a daily quiz, grounded in real test assertions, to learn the codebase he ships into. He scored three out of ten on it, and it's the cheapest learning loop he has found for the era when AI types most of the code.Wed, 06 May 2026 00:00:00 GMTainoreply@mergify.com (Thomas Berdy)https://mergify.com/blog/playwright-auto-wait-element-rerenders/mergify-blog:playwright-auto-wait-element-rerendersWhy Playwright's actionability check can fire on a stale element, the React state-update pattern that triggers it, and the locator strategy that survives the re-render.Tue, 05 May 2026 00:00:00 GMTtestingnoreply@mergify.com (Rémy Duthu)https://mergify.com/blog/vitest-thread-pool-state-leakage/mergify-blog:vitest-thread-pool-state-leakageWhy module singletons survive across tests inside a Vitest worker thread, what the failure looks like, and the two-line config change that gives you per-file isolation.Sun, 03 May 2026 00:00:00 GMTtestingnoreply@mergify.com (Rémy Duthu)https://mergify.com/blog/pytest-fixture-teardown-races/mergify-blog:pytest-fixture-teardown-racesWhy a session-scoped fixture's teardown can pull state out from under tests still using it, and the per-fixture lifecycle discipline that fixes the leak for good.Fri, 01 May 2026 00:00:00 GMTtestingnoreply@mergify.com (Rémy Duthu)https://mergify.com/blog/what-github-webhook-latency-actually-looks-like/mergify-blog:what-github-webhook-latency-actually-looks-likeWe instrumented GitHub webhook delivery latency for ourselves. The p95 stays under 60 seconds in steady state but climbs close to 40 minutes during check-run incidents.Wed, 29 Apr 2026 00:00:00 GMTdeep-divesnoreply@mergify.com (Mehdi Abaakouk)https://mergify.com/blog/cut-your-github-actions-ci-bill/mergify-blog:cut-your-github-actions-ci-billFive concrete levers that move the GitHub Actions bill: runner sizing, caching, test selection, batching, and two-step CI. The math, the tradeoffs, and how to pick the two that actually fit your codebase.Sun, 26 Apr 2026 00:00:00 GMTmerge-queue-cinoreply@mergify.com (Julien Danjou)https://mergify.com/blog/enable-github-merge-queue-actions-setup/mergify-blog:enable-github-merge-queue-actions-setupEnabling GitHub's merge queue is a five-line YAML change plus one repository setting. Here's the working config, the four things that will break the first week, and how to know when you've outgrown it.Sun, 26 Apr 2026 00:00:00 GMTmerge-queue-cinoreply@mergify.com (Julien Danjou)https://mergify.com/blog/github-auto-merge-when-native-is-enough/mergify-blog:github-auto-merge-when-native-is-enoughGitHub has had auto-merge since 2021. The native button handles the simple case well. Here's an honest breakdown of what it does, where it stops being enough, and what to reach for when it does.Sun, 26 Apr 2026 00:00:00 GMTmerge-queue-cinoreply@mergify.com (Julien Danjou)