http.Server.closeAllConnections() does not close upgraded connections, so server.close() waits on every open WebSocket

Fact

After an HTTP upgrade, the socket leaves the HTTP server's own connection tracking but still counts for the underlying net.Server. closeAllConnections() skips it, and the server.close() callback does not fire until every upgraded socket, typically a WebSocket, has ended by itself. Checked on Node 26.

Why it matters

The usual test teardown, close() plus closeAllConnections(), hangs as soon as a test opened a WebSocket, which is exactly when it exercises a real-time server. The run waits for the runner's timeout or a force exit. A test that stops the server to simulate an outage is quietly wrong too: clients stay connected to the old instance, so no outage happens.

How to apply

• Track raw sockets and destroy them on teardown:

  const sockets = new Set();
  server.on('connection', (s) => { sockets.add(s); s.on('close', () => sockets.delete(s)); });
  // teardown
  const closed = new Promise((resolve) => server.close(resolve));
  for (const s of sockets) s.destroy();
  await closed;

• With the ws library, wss.clients.forEach((client) => client.terminate()) covers its own sockets.