lookup: add on-headers

[bjohansebas]

Unfortunately, this module monkey-patches writeHead. It’s an important module in the Express ecosystem and probably in other key packages that need to use it as a hook for writeHead. Adding it to CITGM wouldn’t be a bad idea while we wait for a solution in Node.js core that would allow us to deprecate this module.

cc: @wesleytodd @UlisesGascon @blakeembrey @ctcpip

Checklist

• npm test passes
• tests are included
• documentation is changed or added
• contribution guidelines followed
  here

[ctcpip]

https://github.com/nodejs/citgm/pull/1099/files#r2191222289

[bjohansebas]

I can't resolve the Prettier warning, it seems to be something outside of this PR.

[UlisesGascon]

LGTM! The error in the CI are not related to this change.

I can't resolve the Prettier warning, it seems to be something outside of this PR.

@bjohansebas by running npm run lint:prettier:fix you can see that the changed files are test/reporter/test-reporter-tap.js and test/reporter/test-reporter-junit.js. So we can ignore it 👍

[bjohansebas]

cc: @nodejs/citgm

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.20%. Comparing base (8914dd0) to head (173cd40).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1099   +/-   ##
=======================================
  Coverage   96.20%   96.20%           
=======================================
  Files          29       29           
  Lines        2213     2213           
=======================================
  Hits         2129     2129           
  Misses         84       84           

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[MikeMcC399]

Module on-headers fails in Node.js 26.x when manually tested in https://github.com/nodejs/citgm/actions/workflows/test-module.yml

so it does not currently meet the criteria in CONTRIBUTING for submission.

cc: @blakeembrey

[MikeMcC399]

The issue surfaced by citgm testing against on-headers@1.1.0, released in 2025, and Node.js 26, is resolved in the master branch of on-headers through PR jshttp/on-headers#52 dated May 6, 2026.

I would suggest that on-headers cut a new release to allow citgm to succeed testing with Node.js 26 (and later on Node.js 27 when it is released).

cc: @ctcpip @blakeembrey