test: make sure http pipelining does not emit a warning

See: #37937

test/parallel/test-http-pipelining-no-leak.js

@@ -0,0 +1,49 @@
+'use strict';
+
+const common = require('../common');
+
+// This test ensures Node.js doesn't not emit any warning when receiving
+// pipelined requests
+// https://github.com/nodejs/node/issues/37937
+
+const http = require('http');
+const net = require('net');
+
+const COUNT = 1e4;
+
+let client;
+const server = http
+  .createServer(function(req, res) {
+    setTimeout(function() {
+      req.resume();
+      res.end();
+    }, common.platformTimeout(100));
+  })
+  .listen(0, function() {
+    const req = [
+      'GET / HTTP/1.1',
+      `Host: localhost:${server.address().port}`,
+      'Connection: keep-alive'
+    ].join('\r\n') + '\r\n\r\n';
+
+    client = net.connect(this.address().port, function() {
+      next();
+    });
+    client.resume();
+
+    client.on('drain', next);
+
+    let i = 0;
+    function next() {
+      if (i++ === COUNT + 10) {
+        client.destroy();
+        server.close();
+        return;
+      }
+      if (client.write(req, 'ascii')) {
+        setImmediate(next);
+      }
+    }
+  });
+
+process.on('warning', common.mustNotCall());