[test] Don't use request.allHeaders() in sync page.on() callbacks

[unstubbable]

Alternative for #86740.

This should avoid running into these issues:

request.allHeaders: Target page, context or browser has been closed

The sync headers() method is sufficient for these use cases:

Note that this method does not return security-related headers, including cookie-related ones. You can use request.allHeaders() for complete list of headers that include cookie information.

Note: The other occurrences of request.allHeaders() we have are fine because they're used in page.route() which does handle asynchronous callbacks.

[ijjk]

Failing test suites

Commit: 92af4e8 | About building and testing Next.js

pnpm test-start test/e2e/app-dir/app-basepath/index.test.ts (job)

• app dir - basepath > should only make a single RSC call to the current page (/base/refresh?foo=bar) (DD)

Expand output

● app dir - basepath › should only make a single RSC call to the current page (/base/refresh?foo=bar)

expect(received).toEqual(expected) // deep equality

- Expected  - 0
+ Received  + 1

  Array [
    StringContaining "http://localhost:37225/base/refresh?foo=bar",
+   "http://localhost:37225/base/refresh?foo=bar&_rsc=1yllp",
  ]

  92 |       await browser.waitForIdleNetwork()
  93 |       await retry(async () => {
> 94 |         expect(rscRequests).toEqual([
     |                             ^
  95 |           expect.stringContaining(`${next.url}${path}`),
  96 |         ])
  97 |       })

  at toEqual (e2e/app-dir/app-basepath/index.test.ts:94:29)
  at fn (lib/next-test-utils.ts:797:20)
  at e2e/app-dir/app-basepath/index.test.ts:93:7

[unstubbable]

This seems to have uncovered either a bug or a wrong expectation with cacheComponents enabled. There are actually two RSC requests with different refetch markers in the router state tree being sent:

• ["",{"children":["refresh",{"children":["__PAGE__",{},null,"refetch"]},null,null]},null,null]
• ["",{"children":["refresh",{"children":["__PAGE__",{},null,null]},null,null]},null,"refetch",true]

@ztanner Is this expected?

Repro:

__NEXT_CACHE_COMPONENTS=true NEXT_SKIP_ISOLATE=1 pnpm test-start test/e2e/app-dir/app-basepath/index.test.ts -t 'foo=bar'

[ztanner]

@unstubbable that looks suspiciously like the lazy fetch we do in layout-router when something about the tree mismatches and we don't have anything to render. If that's the case, I think all cases of the lazy fetch occurring is technically a bug (especially in cache components) so we'd need to figure out what's wrong there.

[mischnic]

When I tried it, .headers() didn't include the custom RSC headers.

[unstubbable]

When I tried it, .headers() didn't include the custom RSC headers.

Hm, worked just fine here.