### Question:
AbstractClient { protected static String checkRequiredArg(String arg, String name, CommandLine commandLine, boolean isRequired, String defaultValue) throws ArgsErrorException { String str = commandLine.getOptionValue(arg); if (str == null) { if (isRequired) { String msg = String .format("%s: Required values for option '%s' not provided", IOTDB_CLI_PREFIX, name); System.out.println(msg); System.out.println("Use -help for more information"); throw new ArgsErrorException(msg); } else if (defaultValue == null) { String msg = String .format("%s: Required values for option '%s' is null.", IOTDB_CLI_PREFIX, name); throw new ArgsErrorException(msg); } else { return defaultValue; } } return str; }  static void output(ResultSet res, boolean printToConsole, String statement, ZoneId zoneId);  }### Answer:
@Test public void testCheckRequiredArg() throws ParseException, ArgsErrorException { Options options = AbstractClient.createOptions(); CommandLineParser parser = new DefaultParser(); String[] args = new String[]{"-u", "user1"}; CommandLine commandLine = parser.parse(options, args); String str = AbstractClient .checkRequiredArg(AbstractClient.USERNAME_ARGS, AbstractClient.USERNAME_NAME, commandLine, true, "root"); assertEquals(str, "user1"); args = new String[]{"-u", "root",}; commandLine = parser.parse(options, args); str = AbstractClient .checkRequiredArg(AbstractClient.HOST_ARGS, AbstractClient.HOST_NAME, commandLine, false, "127.0.0.1"); assertEquals(str, "127.0.0.1"); try { str = AbstractClient .checkRequiredArg(AbstractClient.HOST_ARGS, AbstractClient.HOST_NAME, commandLine, true, "127.0.0.1"); } catch (ArgsErrorException e) { assertEquals(e.getMessage(), "IoTDB: Required values for option 'host' not provided"); } try { str = AbstractClient .checkRequiredArg(AbstractClient.HOST_ARGS, AbstractClient.HOST_NAME, commandLine, false, null); } catch (ArgsErrorException e) { assertEquals(e.getMessage(), "IoTDB: Required values for option 'host' is null."); } }