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a41fa47627
Audited every path through the function returned by `flag()` for whether
it opts the caller out of the prerender. No `await connection()` turned
out to be necessary:
- App Router (`flagFn()`, and `evaluate()` without a request) awaits
`headers()` and `cookies()` before calling `decide`. Those are
Request-time APIs, so awaiting a flag already has the effect of
`connection()`. Adding it would mean importing `next/server` — which
`flags/next` avoids at the top level to keep working in Pages Router —
and awaiting one more promise per evaluation, with no change in
behavior.
- The per-request evaluation cache is keyed by the sealed headers object,
so a cache read can only be reached after that request-time read. It
needs no `connection()` of its own.
- Pages Router and routing middleware are handed a request by the caller
and are request-scoped by definition. `connection()` is App Router-only.
- Reading a precomputed value and `evaluate([])` deliberately read
nothing from the request. Adding `connection()` there would break the
entire point of precompute, which is keeping pages prerenderable.
Since the guarantee comes from the SDK rather than from any individual
`decide`, it is easy to break by accident, so this locks it in:
- `packages/flags/src/next/dynamic-rendering.test.ts` asserts which paths
read `headers()`/`cookies()` and which must not — including cache hits,
overrides, bulk evaluation, and precomputed reads.
- `tests/next-1{5,6}` gain an `/app-router-dynamic` route rendering a flag
whose `decide` ignores the request and returns a new value every time.
Next 15 reports it as `ƒ (Dynamic)`, Next 16 (Cache Components) streams
it outside the shell, and an e2e test asserts two requests differ. On
Next 16 the build itself is an assertion: without the SDK's request read
it fails with `next-prerender-random`.
Also documents the behavior for users, in the `flags/next` API reference
and the flags-sdk skill, so nobody adds `await connection()` in front of
a flag evaluation.
No runtime change, hence no changeset.
Co-Authored-By: Dominik Ferber <1765075+dferber90@users.noreply.github.com>
e2e tests
We run e2e tests for multiple versions of Next.js.
We run them for the latest release of every major release from Next.js 13 onwards.
Locally the tests run against the dev server. Playwright will either start the dev server or reuse an already running instance if there is one on the configured port.
In CI the tests run against the production server. We use turbo.json to first build and then start the server.
The test applications are not deployed anywhere to keep the action fast.
Ports
The port of each application indicates the Next.js version
- next-15 runs on 4015
- next-16 runs on 4016
- sveltekit runs on 5173
Developing locally
If you want to write or debug e2e tests for a specific Next.js version you can
Terminal 1
pnpm next-16
Terminal 2
cd tests/next-16pnpm playwright testorpnpm playwright test --ui