@Test
public void metricsRegistered() {

  Configuration conf = new Configuration();
  DecayRpcScheduler scheduler = new DecayRpcScheduler(4, "ipc.8020", conf);
  MetricsSystem metricsSystem = DefaultMetricsSystem.instance();
  DecayRpcSchedulerDetailedMetrics metrics =
      scheduler.getDecayRpcSchedulerDetailedMetrics();
  assertNotNull(metricsSystem.getSource(metrics.getName()));
  scheduler.stop();
  assertNull(metricsSystem.getSource(metrics.getName()));
}