A replay after a reset on a pooled socket can land on another reset socket and return a 502

it("replays on a new connection when every pooled connection is stale", async () => {
  // Answer the first request on a connection and reset the next one, which
  // is what an idle close looks like when it crosses our write. Here both
  // pooled connections do it.
  const handled = new WeakSet<net.Socket>();
  const warming: http.ServerResponse[] = [];
  let resets = 0;
  const backend = trackServer(
    http.createServer((req, res) => {
      if (handled.has(req.socket)) {
        resets++;
        req.socket.resetAndDestroy();
        return;
      }
      handled.add(req.socket);
      if (req.url !== "/warm") return res.end("ok");
      // Hold both warm-up answers so the pool opens two connections.
      warming.push(res);
      if (warming.length === 2) for (const pending of warming) pending.end("ok");
    })
  );
  await listen(backend);
  const backendAddr = backend.address();
  if (!backendAddr || typeof backendAddr === "string") throw new Error("no addr");

  const errors: string[] = [];
  const routes: RouteInfo[] = [{ hostname: "myapp.localhost", port: backendAddr.port }];
  const server = trackServer(
    createProxyServer({
      getRoutes: () => routes,
      proxyPort: TEST_PROXY_PORT,
      onError: (msg) => errors.push(msg),
    })
  );
  await listen(server);

  await Promise.all([
    request(server, { host: "myapp.localhost", path: "/warm" }),
    request(server, { host: "myapp.localhost", path: "/warm" }),
  ]);
  const res = await request(server, { host: "myapp.localhost" });
  expect(res.status).toBe(200);
  expect(res.body).toBe("ok");
  expect(resets).toBe(1);
  expect(errors).toEqual([]);
});