### Question:
JspHelper { public static String getDelegationTokenUrlParam(String tokenString) { if (tokenString == null ) { return ""; } if (UserGroupInformation.isSecurityEnabled()) { return SET_DELEGATION + tokenString; } else { return ""; } } private  JspHelper(); static DatanodeInfo bestNode(LocatedBlocks blks, Configuration conf); static DatanodeInfo bestNode(LocatedBlock blk, Configuration conf); static DatanodeInfo bestNode(DatanodeInfo[] nodes, boolean doRandom,
      Configuration conf); static void streamBlockInAscii(InetSocketAddress addr, String poolId,
      long blockId, Token<BlockTokenIdentifier> blockToken, long genStamp,
      long blockSize, long offsetIntoBlock, long chunkSizeToView,
      JspWriter out, Configuration conf, DataEncryptionKey encryptionKey); static void addTableHeader(JspWriter out); static void addTableRow(JspWriter out, String[] columns); static void addTableRow(JspWriter out, String[] columns, int row); static void addTableFooter(JspWriter out); static void sortNodeList(final List<DatanodeDescriptor> nodes,
                           String field, String order); static void printPathWithLinks(String dir, JspWriter out, 
                                        int namenodeInfoPort,
                                        String tokenString,
                                        String nnAddress
                                        ); static void printGotoForm(JspWriter out,
                                   int namenodeInfoPort,
                                   String tokenString,
                                   String file,
                                   String nnAddress); static void createTitle(JspWriter out, 
                                 HttpServletRequest req, 
                                 String  file); static int string2ChunkSizeToView(String s, int defaultValue); static String getVersionTable(); static String validatePath(String p); static Long validateLong(String value); static String validateURL(String value); static UserGroupInformation getDefaultWebUser(Configuration conf
                                                       ); static UserGroupInformation getUGI(HttpServletRequest request,
      Configuration conf); static UserGroupInformation getUGI(ServletContext context,
      HttpServletRequest request, Configuration conf); static UserGroupInformation getUGI(ServletContext context,
      HttpServletRequest request, Configuration conf,
      final AuthenticationMethod secureAuthMethod,
      final boolean tryUgiParameter); static String getDelegationTokenUrlParam(String tokenString); static String getUrlParam(String name, String val, String paramSeparator); static String getUrlParam(String name, String val, boolean firstParam); static String getUrlParam(String name, String val); static final String CURRENT_CONF; static final String DELEGATION_PARAMETER_NAME; static final String NAMENODE_ADDRESS; }### Answer:
@Test public void testDelegationTokenUrlParam() { conf.set(DFSConfigKeys.HADOOP_SECURITY_AUTHENTICATION, "kerberos"); UserGroupInformation.setConfiguration(conf); String tokenString = "xyzabc"; String delegationTokenParam = JspHelper .getDelegationTokenUrlParam(tokenString); Assert.assertEquals(JspHelper.SET_DELEGATION + "xyzabc", delegationTokenParam); conf.set(DFSConfigKeys.HADOOP_SECURITY_AUTHENTICATION, "simple"); UserGroupInformation.setConfiguration(conf); delegationTokenParam = JspHelper .getDelegationTokenUrlParam(tokenString); Assert.assertEquals("", delegationTokenParam); }