### Question:
MetricsContext { public static Timer.Context start(final String name) { return null == HOLDER.get() ? null : HOLDER.get().timer(MetricRegistry.name(name)).time(); }  static void init(final ShardingProperties shardingProperties); static Timer.Context start(final String name); static void stop(final Timer.Context context); static void clear();  }### Answer:
@Test public void assertStartWhenMetricsDisable() { initDisabledMetrics(); assertNull(MetricsContext.start("name")); }
@Test public void assertStartWhenMetricsEnable() { initEnabledMetrics(); assertNotNull(MetricsContext.start("name")); }