### Question:
DeleteTopicSubCommand implements SubCommand { @Override public void execute(CommandLine commandLine, Options options, RPCHook rpcHook) { DefaultMQAdminExt adminExt = new DefaultMQAdminExt(rpcHook); adminExt.setInstanceName(Long.toString(System.currentTimeMillis())); try { String topic = commandLine.getOptionValue('t').trim(); if (commandLine.hasOption('c')) { String clusterName = commandLine.getOptionValue('c').trim(); adminExt.start(); deleteTopic(adminExt, clusterName, topic); return; } ServerUtil.printCommandLineHelp("mqadmin " + this.commandName(), options); } catch (Exception e) { e.printStackTrace(); } finally { adminExt.shutdown(); } }  static void deleteTopic(final DefaultMQAdminExt adminExt,
        final String clusterName,
        final String topic
    ); @Override String commandName(); @Override String commandDesc(); @Override Options buildCommandlineOptions(Options options); @Override void execute(CommandLine commandLine, Options options, RPCHook rpcHook);  }### Answer:
@Test public void testExecute() { DeleteTopicSubCommand cmd = new DeleteTopicSubCommand(); Options options = ServerUtil.buildCommandlineOptions(new Options()); String[] subargs = new String[] {"-t unit-test", "-c default-cluster"}; final CommandLine commandLine = ServerUtil.parseCmdLine("mqadmin " + cmd.commandName(), subargs, cmd.buildCommandlineOptions(options), new PosixParser()); assertThat(commandLine.getOptionValue('t').trim()).isEqualTo("unit-test"); assertThat(commandLine.getOptionValue("c").trim()).isEqualTo("default-cluster"); }