### Question:
ConsumerGroupTopicServiceImpl extends AbstractBaseService<ConsumerGroupTopicEntity> implements CacheUpdateService, ConsumerGroupTopicService, TimerService { @Override public void start() { if (startFlag.compareAndSet(false, true)) { updateCache(); executor.submit(new Runnable() { @Override public void run() { while (isRunning) { try { updateCache(); } catch (Exception e) { log.error("ConsumerGroupTopicService_updateCache_error", e); } Util.sleep(soaConfig.getMqConsumerGroupTopicCacheInterval()); } } }); } }  @Override void start(); @Override void updateCache(); @Override void forceUpdateCache(); @Override Map<Long, Map<String, ConsumerGroupTopicEntity>> getCache(); @Override Map<String, ConsumerGroupTopicEntity> getGroupTopic(); @Override void deleteByConsumerGroupId(long consumerGroupId); @Override void deleteByOriginTopicName(long consumerGroupId, String originTopicName); @Override List<String> getFailTopicNames(long consumerGroupId); @Override ConsumerGroupTopicEntity getCorrespondConsumerGroupTopic(Map<String, Object> parameterMap); @Override void updateEmailByGroupName(String groupName, String alarmEmails); @PreDestroy @Override void stop(); @Override String info(); @Override String getCacheJson(); @Override Map<String, List<ConsumerGroupTopicEntity>> getTopicSubscribeMap(); @Transactional(rollbackFor = Exception.class) @Override ConsumerGroupTopicCreateResponse subscribe(ConsumerGroupTopicCreateRequest consumerGroupTopicCreateRequest); @Override ConsumerGroupTopicCreateResponse subscribe(ConsumerGroupTopicCreateRequest consumerGroupTopicCreateRequest,Map<String, ConsumerGroupEntity> consumerGroupMap); @Override ConsumerGroupTopicEntity createConsumerGroupTopic(
			ConsumerGroupTopicCreateRequest consumerGroupTopicCreateRequest); @Transactional(rollbackFor = Exception.class) @Override ConsumerGroupTopicDeleteResponse deleteConsumerGroupTopic(long consumerGroupTopicId);  }### Answer:
@Test public void startTest() { List<ConsumerGroupTopicEntity> consumerGroupEntities = new ArrayList<ConsumerGroupTopicEntity>(); ConsumerGroupTopicEntity consumerGroupEntity = new ConsumerGroupTopicEntity(); consumerGroupEntity.setConsumerGroupName("test"); consumerGroupEntity.setTopicName("test"); consumerGroupEntity.setId(1L); consumerGroupEntities.add(consumerGroupEntity); when(consumerGroupTopicRepository.getAll()).thenReturn(consumerGroupEntities); consumerGroupTopicServiceImpl.start(); assertEquals(1, consumerGroupTopicServiceImpl.consumerGroupTopicRefMap.get().size()); consumerGroupTopicServiceImpl.stop(); }