@Test
  public void simpleDiscoverable() throws Exception {
    Map.Entry<DiscoveryService, DiscoveryServiceClient> entry = create();
    DiscoveryService discoveryService = entry.getKey();
    DiscoveryServiceClient discoveryServiceClient = entry.getValue();

    // Register one service running on one host:port
    Cancellable cancellable = register(discoveryService, "foo", "localhost", 8090);

    // Discover that registered host:port.
    ServiceDiscovered serviceDiscovered = discoveryServiceClient.discover("foo");
    Assert.assertTrue(waitTillExpected(1, serviceDiscovered));

    Discoverable discoverable =
        new Discoverable() {
          @Override
          public String getName() {
            return "foo";
          }

          @Override
          public InetSocketAddress getSocketAddress() {
            return new InetSocketAddress("localhost", 8090);
          }
        };

    // Check it exists.
    Assert.assertTrue(serviceDiscovered.contains(discoverable));

    // Remove the service
    cancellable.cancel();

    // There should be no service.
    Assert.assertTrue(waitTillExpected(0, serviceDiscovered));

    Assert.assertFalse(serviceDiscovered.contains(discoverable));
  }