public void registerCommands(Map<String, CommandHandler> handlerMap) {
        if (handlerMap != null) {
            for (Entry<String, CommandHandler> e : handlerMap.entrySet()) {
                registerCommand(e.getKey(), e.getValue());
            }
        }
    }
@Test
    public void testRegisterCommands() {
        Map<String, CommandHandler> handlerMap = null;

        // If handlerMap is null, no handler added in handlerMap
        httpServer.registerCommands(handlerMap);
        assertEquals(0, HttpServer.handlerMap.size());

        // Add handler from CommandHandlerProvider
        handlerMap = CommandHandlerProvider.getInstance().namedHandlers();
        httpServer.registerCommands(handlerMap);
        // Check same size
        assertEquals(handlerMap.size(), HttpServer.handlerMap.size());
        // Check not same reference
        assertTrue(handlerMap != HttpServer.handlerMap);
    }