HelpTelnetHandler implements TelnetHandler { @Override public String telnet(AbstractChannel channel, String message) { StringBuffer result = new StringBuffer(); if (StringUtils.isNotBlank(message)) { TelnetHandler handler = TelnetHandlerFactory.getHandler(message); if (handler != null) { result.append(handler.getCommand()).append(LINE) .append(handler.getDescription()).append(LINE); } else { result.append("Not found command : " + message); } } else { result.append("The supported command include:").append(LINE); for (Map.Entry<String, TelnetHandler> entry : TelnetHandlerFactory.getAllHandlers().entrySet()) { result.append(entry.getKey()).append(" "); } result.append(LINE); } return result.toString(); }  @Override String getCommand(); @Override String telnet(AbstractChannel channel, String message); @Override String getDescription();  }
@Test public void telnet() throws Exception { Assert.assertNotNull(new HelpTelnetHandler().telnet(null, "")); Assert.assertNotNull(new HelpTelnetHandler().telnet(null, null)); Assert.assertNotNull(new HelpTelnetHandler().telnet(null, "xx")); }