@Test
    public void pushMessage() {
        Map<String, String> optional = new HashMap<String, String>();
        optional.put(Channel.USER_ID, userId);
        optional.put(Channel.MESSAGE_TYPE, String.valueOf(1));
        
        Channel channel = new Channel();
        channel.initialize(apiKey, secretKey, null);
//       
        int pushType = 3; 
        String messages = "{ 'title': 'hello " + new Date() + "' , 'description': 'hello'}";
        String messageKey = "msg_key";
        
        JSONObject result = channel.pushMessage(pushType, messages, messageKey, optional);
        if (channel.errcode ==0) {
            Assert.assertNotNull(result);
            System.out.println(result);
        }
        else {
            System.out.println("error_code: " + channel.errcode + "; error_msg: " + channel.errmsg);
        }
    }