improve test for issue #3410 by spawning a custom server

test/issue-3410.js

@@ -1,16 +1,47 @@
 'use strict'
 
+const { tspl } = require('@matteo.collina/tspl')
+const { fork } = require('node:child_process')
+const { resolve: pathResolve } = require('node:path')
 const { test } = require('node:test')
-const { eventLoopBlocker } = require('./utils/event-loop-blocker')
 const { Agent, fetch, setGlobalDispatcher } = require('..')
+const { eventLoopBlocker } = require('./utils/event-loop-blocker')
 
 test('https://github.com/nodejs/undici/issues/3356', async (t) => {
+  t = tspl(t, { plan: 1 })
+
+  // Spawn a server in a new process to avoid effects from the blocking event loop
+  const {
+    serverProcess,
+    address
+  } = await new Promise((resolve, reject) => {
+    const childProcess = fork(
+      pathResolve(__dirname, './utils/hello-world-server.js'),
+      [],
+      { windowsHide: true }
+    )
+
+    childProcess.on('message', (address) => {
+      resolve({
+        serverProcess: childProcess,
+        address
+      })
+    })
+    childProcess.on('error', err => {
+      reject(err)
+    })
+  })
+
   const connectTimeout = 2000
   setGlobalDispatcher(new Agent({ connectTimeout }))
 
-  const fetchPromise = fetch('http://www.example.org/')
+  const fetchPromise = fetch(address)
 
   eventLoopBlocker(3000)
 
-  await fetchPromise
+  const response = await fetchPromise
+
+  t.equal(await response.text(), 'Hello World')
+
+  serverProcess.kill('SIGKILL')
 })

test/utils/hello-world-server.js

@@ -0,0 +1,30 @@
+'use strict'
+
+const { createServer } = require('node:http')
+const hostname = '127.0.0.1'
+
+const server = createServer(async (req, res) => {
+  res.statusCode = 200
+  res.setHeader('Content-Type', 'text/plain')
+
+  await sendInDelayedChunks(res, 'Hello World', 125)
+  res.end()
+})
+
+async function sendInDelayedChunks (res, payload, delay) {
+  const chunks = payload.split('')
+
+  for (const chunk of chunks) {
+    await new Promise(resolve => setTimeout(resolve, delay))
+
+    res.write(chunk)
+  }
+}
+
+server.listen(0, hostname, () => {
+  if (process.send) {
+    process.send(`http://${hostname}:${server.address().port}/`)
+  } else {
+    console.log(`http://${hostname}:${server.address().port}/`)
+  }
+})