@Test(expected = IllegalArgumentException.class)
public void testNnElementsNotSpecified()  throws IllegalArgumentException {

   Map<String, String> configs = new HashMap<String, String>();
   configs.put("username", "hdfsuser");
   configs.put("password", "hdfsuser");
   configs.put("hadoop.security.authentication", "simple");
   configs.put("fs.default.name", "hdfs://hwqe-1425428405");
   configs.put("dfs.nameservices", "hwqe-1425428405");
   configs.put("dfs.client.failover.proxy.provider.hwqe-1425428405",
     "org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider");
   HdfsClient.validateConnectionConfigs(configs);
}