test: refactor test-http-agent-timeout-option

[lpinca]

Fix flakyness caused by usage of a non-routable IP address.

Refs: #25488 (comment)

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines

[nodejs-github-bot]

@lpinca build started: https://ci.nodejs.org/blue/organizations/jenkins/node-test-pull-request-lite-pipeline/detail/node-test-pull-request-lite-pipeline/2470/pipeline

[lpinca]

CI: https://ci.nodejs.org/job/node-test-pull-request/20486/
cc: @targos

[Trott]

Resume Build CI: https://ci.nodejs.org/job/node-test-pull-request/20533/ 🤘

[Trott]

Would like to fast-track this since it's fixing a flaky test. (Just got it myself in https://ci.nodejs.org/job/node-test-binary-arm/5905/RUN_SUBSET=4,label=pi2-docker/console.)

Please 👍 here to fast-track.

[Trott]

Landed in 988482e

[lpinca]

Was writing a simpler version without establishing a TCP connection but I did not make it in time.

'use strict';

const { mustCall } = require('../common');
const { strictEqual } = require('assert');
const { Agent, get } = require('http');

// Test that the listener that forwards the `'timeout'` event from the socket to
// the `ClientRequest` instance is added to the socket when the `timeout` option
// of the `Agent` is set.

const request = get({
  agent: new Agent({ timeout: 50 }),
  lookup: () => {}
});

request.on('socket', mustCall((socket) => {
  strictEqual(socket.timeout, 50);

  const listeners = socket.listeners('timeout');

  strictEqual(listeners.length, 1);
  strictEqual(listeners[0], request.timeoutCb);
}));

@Trott @gireeshpunathil what you think, does it worth to effort to refactor it again?

[gireeshpunathil]

this looks good, but given the premise is CI stability and that is established with the one that is landed may be leave it at that, visit again if it flakes?

[lpinca]

Yes, the only reason was to make it faster, no need to wait 500 ms or whatever the the timeout is, it should only test that the listener is added.