@Test
public void testAddLatency() {

  Map<String, List<Double>> stats = Maps.newHashMap();
  String id = "spout";
  double lat = 0.01;
  MetricsUtils.addLatency(stats, id, lat);
  assertThat(stats).containsKey(id);
  assertThat(stats.get(id)).isNotNull().contains(lat);
}