test: add failing test for MockHttpSocket memory leak

.gitignore

@@ -5,3 +5,4 @@ node_modules
 lib
 package-lock.json
 .idea
+*.heapsnapshot

simple-git-hooks.js

@@ -1,4 +1,4 @@
 module.exports = {
-  'prepare-commit-msg': `grep -qE '^[^#]' .git/COMMIT_EDITMSG || (exec < /dev/tty && yarn cz --hook || true)`,
-  'commit-msg': 'yarn commitlint --edit $1',
+  'prepare-commit-msg': `grep -qE '^[^#]' .git/COMMIT_EDITMSG || (exec < /dev/tty && pnpm cz --hook || true)`,
+  'commit-msg': 'pnpm commitlint --edit $1',
 }

src/interceptors/ClientRequest/MockHttpSocket.ts

@@ -128,7 +128,13 @@ export class MockHttpSocket extends MockSocket {
 
     // Once the socket is finished, nothing can write to it
     // anymore. It has also flushed any buffered chunks.
-    this.once('finish', () => this.requestParser.free())
+    this.once('finish', () => {
+      this.requestParser.free()
+      // @ts-ignore
+      this.parser = null
+      // @ts-ignore
+      this._httpMessage.parser = null
+    })
 
     if (this.baseUrl.protocol === 'https:') {
       Reflect.set(this, 'encrypted', true)

test/modules/http/http-memory-worker.js

@@ -0,0 +1,33 @@
+const v8 = require('node:v8')
+const path = require('node:path')
+const http = require('node:http')
+const { workerData, parentPort } = require('node:worker_threads')
+const {
+  ClientRequestInterceptor,
+} = require('../../../lib/interceptors/ClientRequest')
+
+const interceptor = new ClientRequestInterceptor()
+interceptor.apply()
+
+const pendingRequests = []
+
+for (let i = 0; i < workerData.requestCount; i++) {
+  pendingRequests.push(
+    new Promise((resolve, reject) => {
+      http
+        .get(workerData.serverUrl, (response) => {
+          response.on('data', () => {})
+          response.on('error', (error) => reject(error))
+          response.on('end', () => resolve())
+        })
+        .on('error', (error) => reject(error))
+    })
+  )
+}
+
+globalThis.gc?.()
+v8.writeHeapSnapshot(workerData.snapshotPath)
+
+Promise.allSettled(pendingRequests).then(() => {
+  parentPort.postMessage('complete')
+})

test/modules/http/http-memory.test.ts

@@ -0,0 +1,50 @@
+// @vitest-environment node
+import fs from 'node:fs'
+import path from 'node:path'
+import { Worker } from 'node:worker_threads'
+import { HttpServer } from '@open-draft/test-server/http'
+import { it, expect, beforeAll, afterAll } from 'vitest'
+import { DeferredPromise } from '@open-draft/deferred-promise'
+
+const server = new HttpServer((app) => {
+  app.get('/', (_req, res) => res.status(200).end())
+})
+
+beforeAll(async () => {
+  await server.listen()
+})
+
+afterAll(async () => {
+  await server.close()
+})
+
+it(
+  'does not retain the MockHttpSocket instance',
+  async () => {
+    const snapshotPath = path.resolve(__dirname, 'http-memory.heapsnapshot')
+
+    // Spawn the usage scenario in a worker so the test doesn't affect the heap.
+    const worker = new Worker(
+      path.resolve(__dirname, './http-memory-worker.js'),
+      {
+        workerData: {
+          requestCount: 10_000,
+          serverUrl: server.http.url('/'),
+          snapshotPath,
+        },
+        stderr: true,
+        stdout: true,
+      }
+    )
+
+    const completePromise = new DeferredPromise<void>()
+    worker.once('message', () => completePromise.resolve())
+    worker.on('error', (error) => completePromise.reject(error))
+
+    await completePromise
+
+    const snapshotStats = await fs.promises.stat(snapshotPath)
+    expect(snapshotStats.size / 1_000_000).toBeLessThanOrEqual(100)
+  },
+  { timeout: 10_000 }
+)