got "incorrect header check" when invoke pako.inflate during websocket test

[wallenZhao2046]

I am executing a websocket testing using K6.
when handling ws response, I need to inflate the content. and I tried to use pako to do that.
The following is my script. I found pako can't deflate string and inflate either.
I tried the same code in node.js, fount it worked well. Is there anything wrong?

import ws from "k6/ws";
import { check } from "k6";
import pako from './pako.js';

export default function() {
  var url = "ws://api.xxx.pro/ws";
  var params = { "tags": { "my_tag": "hello" } };
  var res = ws.connect(url, params, function(socket) {
    socket.on('open', function() {
      socket.send('WebSocket rocks');

     //begin--------
     // the following code is to test whether pako working in K6
     let data = { ping: "12345678"};
     console.log(JSON.stringify(data));
     let binStr = pako.deflate(JSON.stringify(data), {to:'string'});
     console.log(binStr);
     let text = pako.inflate(binStr, {
            to: 'string'
     });
     //end: ------------

    });

    socket.on('message', function(data) {
      // .....
    }); 

the error message is

INFO[0004] !!!!!!!

ERRO[0004] incorrect header check
	at inflate (/Users/zh/workspace/test_files/k6_files/pako_out.js:803:45(24))
	at /Users/zh/workspace/test_files/k6_files/ws_base_test.js:24:50(76)

[na--]

This seems like it may be an issue with the bower version of the pako library itself. Executing bower install pako and then this script with k6:

import pako from './bower_components/pako/dist/pako.js';

export default function () {
    let data = { ping: "12345678" };

    let json = JSON.stringify(data);
    console.log(json);

    let binStr = pako.deflate(json);
    console.log(binStr);

    let text = pako.inflate(binStr);
    console.log(text);

    console.log(String.fromCharCode.apply(null, text));
}

works as expected and gives me:

INFO[0000] {"ping":"12345678"}                          
INFO[0003] 120,156,171,86,42,200,204,75,87,178,82,50,52,50,54,49,53,51,183,80,170,5,0,54,213,5,13 
INFO[0003] 123,34,112,105,110,103,34,58,34,49,50,51,52,53,54,55,56,34,125 
INFO[0003] {"ping":"12345678"}

As soon as I try to add {to:'string'} I get the error you mention and using raw: true as suggested here just gives me other errors.

[wallenZhao2046]

@na-- It works well here. Thanks a lot ! By the way, I got a reply message when I connected to a websocket server, and I printed it in console got a strang string code like "�V*��KW�245215�0145�0�����". How can I uncompress it? Would you please give me any idea?

[na--]

Sorry, I'm not sure what the reason is, maybe the server just uses the websockets to send some sort of binary data? In any case, that discussion is something that's more suited to the #support channel of the k6 slack, so I'm closing this issue for now.

[wallenZhao2046]

@na-- You are right. This issue is not a bug. Thanks for your reply.

[na--]

As seen here, it seems like this could indeed be a bug in the goja runtime or somewhere in the JavaScript stack (babel, core.js/etc.), so I'm reopening this issue.

[mstoykov]

The error in StackOverflow would probably be as data is a string but after #1841 it should now be possible to get it as ByteArray and use that?

[mstoykov]

I am closing this as the error that was provided in the original report is no longer happening since k6 v0.26.2 but was present up to v0.25.1.

This likely was fixed by a goja update at some point and we just didn't notice