// Regression for #3311: subscribe FIRST, then migrate the slot in place.
    // The server pushes SUNSUBSCRIBE to the already-subscribed client, which
    // must drive the cluster to rediscover and reattach the listener on the
    // new owner. The dead `server-sunsubscribe` listener meant this never
    // happened and the subscription was silently lost after migration.
    testUtils.testWithCluster('should resubscribe a sharded channel after in-place slot migration (#3311)', async cluster => {
      const SLOT = 10328, // slot of `channel`
        migrating = cluster.slots[SLOT].master,
        importing = cluster.masters.find(master => master !== migrating)!,
        [migratingClient, importingClient] = await Promise.all([
          cluster.nodeClient(migrating),
          cluster.nodeClient(importing)
        ]);

      const listener = spy();

      // subscribe BEFORE migration -> the sharded PubSub client attaches to `migrating`
      await cluster.sSubscribe('channel', listener);

      // move the slot in-place to `importing`; `migrating` loses the slot and
      // pushes SUNSUBSCRIBE to the subscribed client
      await Promise.all([
        migratingClient.clusterDelSlots(SLOT),
        importingClient.clusterDelSlots(SLOT),
        importingClient.clusterAddSlots(SLOT),
        migratingClient.clusterSetSlot(SLOT, 'NODE', importing.id),
        importingClient.clusterSetSlot(SLOT, 'NODE', importing.id)
      ]);

      // the reattach is async and sharded PubSub does not buffer, so
      // publish until the resubscribed listener receives the message.
      // With the bug this never reattaches and the loop exhausts -> assertion fails.
      for (let i = 0; i < 50 && !listener.called; i++) {
        await cluster.sPublish('channel', 'message');
        await setTimeout(100);
      }

      assert.ok(listener.calledWithExactly('message', 'channel'));
    }, {
      serverArguments: [],
      minimumDockerVersion: [7]
    });