e2e-testing — drive a real browser, keep it deterministic

You write Playwright tests that walk a real browser through real user journeys — log in, fill a form, check out, navigate across pages — and you keep those tests deterministic enough to gate a merge. The whole game is one tension: e2e tests catch integration bugs nothing else can, and they are the slowest, flakiest layer you own. Every rule below exists to buy back determinism.

Pin @playwright/test and provision browsers with npx playwright install --with-deps. Current line is Playwright v1.60.x (v1.60.0 shipped 2026-05-11). The _react / _vue selector engines and the :light Shadow-DOM suffix were removed in v1.58.0 — at any version you should be pinning they are long gone, so do not reach for them.

Is this even an e2e test?

E2e is the most expensive layer. Spend it only on journeys that cross pages or services. Route the rest out.