test: add new scenario for async-local storage

Add a new scenario of multiple clients sharing a single data
callback function managing their response data through
AsyncLocalStorage APIs

Refs: nodejs#32063
Refs: nodejs#32060
Refs: nodejs#32062 (comment)

Co-authored-by: Gireesh Punathil <[email protected]>

test/parallel/test-async-local-storage-http-multiclients.js

@@ -0,0 +1,64 @@
+'use strict';
+const common = require('../common');
+
+const assert = require('assert');
+const { AsyncLocalStorage } = require('async_hooks');
+const http = require('http');
+const cls = new AsyncLocalStorage();
+const NUM_CLIENTS = 10;
+
+// Run multiple clients that receive data from a server
+// in multiple chunks, in a single non-closure function.
+// Use the AsyncLocalStorage (ALS) APIs to maintain the context
+// and data download. Make sure that individual clients
+// receive their respective data, with no conflicts.
+
+// Set up a server, that sends large buffers of data, filled
+// with cardinal numbers, increasing per request
+let index = 0;
+const server = http.createServer((q, r) => {
+  // Send a large chunk as response, otherwise the data
+  // may be coalesced, and the callback in the client
+  // may be called only once, defeating the purpose of test
+  r.end((index++).toString().repeat(1024 * 1024));
+});
+
+server.listen(0, common.mustCall(() => {
+  for (let i = 0; i < NUM_CLIENTS; i++) {
+    cls.run(new Map(), common.mustCall(() => {
+      const options = { port: server.address().port };
+      const req = http.get(options, common.mustCall((res) => {
+        const store = cls.getStore();
+        store.set('data', '');
+
+        // Make ondata and onend non-closure
+        // functions and fully dependent on ALS
+        res.on('data', ondata);
+        res.on('end', onend);
+      }));
+      req.end();
+    }));
+  }
+}));
+
+// Accumulate the instantaneous data with the store data
+function ondata(d) {
+  const store = cls.getStore();
+  assert.notStrictEqual(store, undefined);
+  let chunk = store.get('data');
+  chunk += d;
+  store.set('data', chunk);
+}
+
+// Retrieve the store data, and test for homogeneity
+let endCount = 0;
+function onend() {
+  const store = cls.getStore();
+  assert.notStrictEqual(store, undefined);
+  const chunk = store.get('data');
+  const re = new RegExp(chunk[0], 'g');
+  assert.strictEqual(chunk.replace(re, '').length, 0);
+  if (++endCount === NUM_CLIENTS) {
+    server.close();
+  }
+}