### Question:
Watchdog { public void watch(final Watchable watchable) { registry.add(watchable); LOGGER.debug("Watchable cache '{}' registered", watchable.name()); } private  Watchdog(final ScheduledExecutorService scheduler); static Watchdog create(); void watch(final Watchable watchable); void unwatch(final Watchable watchable); void init();  }### Answer:
@Test public void testMustProbeAllRegisteredWatchables() { watchdog.watch(cache1); watchdog.watch(cache2); scheduler.trigger(); verify(cache1).probeLiveness(); verify(cache2).probeLiveness(); }