### Question:
ConfigUtil { public String getCluster() { return cluster; } 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 testApolloCluster() throws Exception { String someCluster = "someCluster"; System.setProperty(ConfigConsts.APOLLO_CLUSTER_KEY, someCluster); ConfigUtil configUtil = new ConfigUtil(); assertEquals(someCluster, configUtil.getCluster()); }