How to write jest unit test cases for socket.io in Nodejs

I installed socket.io in my node js and established a connection and emitting events from NodeJs and it is working fine. Check the below code that I have written.

const io = require('socket.io')(server, {
cors: {
    origin: "http://localhost:4200",
    methods: ["GET", "POST"]
}
});
io.on('connection', (socket)=>{
console.log('Client connected');
io.emit('message', items);
socket.on('message', data => {
    console.log('this is server data', data);
    items.push(data);
    io.emit('message', items);
})

Now everything is working fine from front end and backend as well except for unit test cases.

I'm not able to cover the connection part of the socket.io in NodeJS.

I'm using Jest to do that. I used the example provided in the below link :

https://socket.io/docs/v4/testing/#example-with-jest

It is not throwing any error but the code for socket connection is not getting covered at all.