/** @throws Exception If failed. */
  public void testTopologyListener() throws Exception {
    final Collection<UUID> added = new ArrayList<>(1);
    final Collection<UUID> rmvd = new ArrayList<>(1);

    final CountDownLatch addedLatch = new CountDownLatch(1);
    final CountDownLatch rmvLatch = new CountDownLatch(1);

    assertEquals(NODES_CNT, client.compute().refreshTopology(false, false).size());

    GridClientTopologyListener lsnr =
        new GridClientTopologyListener() {
          @Override
          public void onNodeAdded(GridClientNode node) {
            added.add(node.nodeId());

            addedLatch.countDown();
          }

          @Override
          public void onNodeRemoved(GridClientNode node) {
            rmvd.add(node.nodeId());

            rmvLatch.countDown();
          }
        };

    client.addTopologyListener(lsnr);

    try {
      Grid g = startGrid(NODES_CNT + 1);

      UUID id = g.localNode().id();

      assertTrue(addedLatch.await(2 * TOP_REFRESH_FREQ, MILLISECONDS));

      assertEquals(1, added.size());
      assertEquals(id, F.first(added));

      stopGrid(NODES_CNT + 1);

      assertTrue(rmvLatch.await(2 * TOP_REFRESH_FREQ, MILLISECONDS));

      assertEquals(1, rmvd.size());
      assertEquals(id, F.first(rmvd));
    } finally {
      client.removeTopologyListener(lsnr);

      stopGrid(NODES_CNT + 1);
    }
  }