### Question:
ConfigUtil { public long getLongPollingInitialDelayInMills() { return longPollingInitialDelayInMills; } ConfigUtil(); String getAppId(); String getDataCenter(); String getCluster(); Env getApolloEnv(); String getLocalIp(); String getMetaServerDomainName(); int getConnectTimeout(); int getReadTimeout(); int getRefreshInterval(); TimeUnit getRefreshIntervalTimeUnit(); int getLoadConfigQPS(); int getLongPollQPS(); long getOnErrorRetryInterval(); TimeUnit getOnErrorRetryIntervalTimeUnit(); String getDefaultLocalCacheDir(); boolean isInLocalMode(); boolean isOSWindows(); long getMaxConfigCacheSize(); long getConfigCacheExpireTime(); TimeUnit getConfigCacheExpireTimeUnit(); long getLongPollingInitialDelayInMills(); boolean isAutoUpdateInjectedSpringPropertiesEnabled();  }### Answer:
@Test public void testCustomizeLongPollingInitialDelayInMills() throws Exception { long someLongPollingDelayInMills = 1; System.setProperty("apollo.longPollingInitialDelayInMills", String.valueOf(someLongPollingDelayInMills)); ConfigUtil configUtil = new ConfigUtil(); assertEquals(someLongPollingDelayInMills, configUtil.getLongPollingInitialDelayInMills()); }
@Test public void testCustomizeInvalidLongPollingInitialDelayInMills() throws Exception { String someInvalidLongPollingDelayInMills = "a"; System.setProperty("apollo.longPollingInitialDelayInMills", someInvalidLongPollingDelayInMills); ConfigUtil configUtil = new ConfigUtil(); assertTrue(configUtil.getLongPollingInitialDelayInMills() > 0); }