@Test
public void healthServing() throws Exception {

    // Generate a unique in-process server name.
    String serverName = InProcessServerBuilder.generateName();
    HealthCheckAggregator hca = mock(HealthCheckAggregator.class);
    CompletableFuture<HealthCheckStatus> hcsf = mock(CompletableFuture.class);
    HealthCheckStatus hcs = mock(HealthCheckStatus.class);
    when(hcs.isHealthy()).thenReturn(true);
    when(hcsf.get()).thenReturn(hcs);
    when(hca.check()).thenReturn(hcsf);
    HealthServiceImpl healthyService = new HealthServiceImpl(hca);
    addService(serverName, healthyService);
    HealthGrpc.HealthBlockingStub blockingStub = HealthGrpc.newBlockingStub(
            // Create a client channel and register for automatic graceful shutdown.
            grpcCleanup.register(InProcessChannelBuilder.forName(serverName).directExecutor().build()));
    HealthCheckResponse reply = blockingStub.check(HealthCheckRequest.newBuilder().build());
    assertEquals(HealthCheckResponse.ServingStatus.SERVING, reply.getStatus());
}