The rail animates its width from w-16 to w-64, and the labels laid out against the growing width: every row overran the nav and multi-word labels wrapped, so the nav's overflow-y-auto painted a vertical and a horizontal scrollbar for the length of the transition. Lay the expanded column out at its final width from the first frame and let the rail clip it. The final layout is unchanged; the column fills the expanded rail exactly. A unit test pins the structure and an e2e spec samples the nav on every frame of a real expand and collapse.
e2e/
End-to-end browser tests. Playwright 1.60 drives a production build of the app against a real PostgreSQL, with @axe-core/playwright for accessibility assertions. This is the heaviest test tier; CI runs it on every PR, and locally it is worth running when a change touches a UI flow.
Running
pnpm e2e
The Playwright config (../playwright.config.ts) builds the app (next build) and brings up Postgres before the specs run; setup/global-setup.ts seeds the auth + fixture state. The suite is not part of the fast local gate (typecheck / lint / test) — it surfaces at PR CI, so expect responsive/wizard/nav reworks to flag here first.
Layout
setup/—test.ts(the suite'stest+expectentry point),global-setup.ts(auth + DB seeding),test-helpers.ts(shared login + navigation helpers).utils/— fixtures such asmock-dashboard-snapshot.ts.fixtures/— synthetic payloads a journey uploads, built in code rather than committed as blobs so the content stays reviewable (apple-health-export.ts).*.spec.ts— one spec per flow: auth/login/redirect, dashboard, charts, the medication-wizard cadences (medications-wizard-*), insights generation + scroll restoration, doctor report, settings, mobile-viewport consistency, locale switch, accessibility (a11y.spec.ts), and thev1427-*regression set.
Conventions
Import test and expect from ./setup/test, never from @playwright/test — types (Page, Route, …) still come from the package. The entry point extends Playwright's test with an automatic fixture that drops route handlers and page listeners after every test, so a handler left in flight cannot fail the test it belonged to once the context closes. src/__tests__/e2e-route-cleanup-guard.test.ts enforces the import boundary.
Assert against stable data-* attributes (data-slot, data-display-step, root display attrs), not viewport-dependent visible text. Responsive sm:hidden UI changes break getByText on desktop while the underlying element is still present — anchoring on data attributes keeps the specs stable across breakpoints. See ../CLAUDE.md.