### Question:
HealthServiceImpl extends BaseService implements HealthService, Stoppable { @Override public void checkInOk(final String name) { if (debug) logger.debug("HealthService::checkInOk() {} ", name); final NodeHealthStat nodeHealthStat = getServiceHealthStat(name); nodeHealthStat.setLastCheckIn(super.time); nodeHealthStat.setReason(null); nodeHealthStat.setStatus(HealthStatus.PASS); super.incrementCount("checkin"); onCheckIn.ifPresent(checkIn -> checkIn.accept(BeanUtils.copy(nodeHealthStat))); } HealthServiceImpl(final String healthPrefix,
                             final Reactor reactor,
                             final Timer timer,
                             final StatsCollector statsCollector,
                             final long recheckInterval,
                             final TimeUnit timeUnit,
                             final List<HealthCheckJob> healthCheckJobs,
                             final Optional<Consumer<NodeHealthStat>> onFail,
                             final Optional<Consumer<NodeHealthStat>> onWarn,
                             final Optional<Consumer<NodeHealthStat>> onCheckIn); @Override void register(final String name, final long ttl, final TimeUnit timeUnit); @Override void registerNoTtl(final String name); @Override void checkInOk(final String name); @Override void checkIn(final String name, final HealthStatus status); @Override void failWithReason(final String name, final HealthFailReason reason); @Override void failWithError(final String name, final Throwable error); @Override void warnWithReason(final String name, final HealthFailReason reason); @Override void warnWithError(final String name, final Throwable error); @Override boolean ok(); @Override List<String> findHealthyNodes(); @Override List<String> findAllNodes(); @Override List<String> findAllNodesWithStatus(final HealthStatus queryStatus); @Override List<String> findNotHealthyNodes(); @Override List<NodeHealthStat> loadNodes(); @Override void unregister(String nodeName); @Override void stop();  }### Answer:
@Test public void testCheckInOk() throws Exception { healthService.register("foo", 1, TimeUnit.SECONDS); healthService.checkInOk("foo"); assertTrue("foo is found among the healthy ", healthService.findHealthyNodes().stream().anyMatch(s -> s.equals("foo"))); }