Testing on backpressure of Transform. Somehow with this simple code, drain is not working. It just hung. Any help is appreciated.

Code is below, if you run the code, you will notice it hung.

const stream = require('stream'); const pipelineAsync = require('util').promisify(stream.pipeline);

class MyTransform extends stream.Transform {
    constructor() {
        super({
            objectMode: true,
            writableHighWaterMark: 10,
        });
    }
    _transform(chunk, enc, cb) {
        console.log(`transform`, chunk)
        const nextData = `T${chunk}`;

        if (this.push(nextData)) {
            return cb();
        }
        
        console.log('!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! back pressured')
        this.once('drain', () => {
            console.log('drained======================================>  This never fires on time')
            cb();
        })
        /*
        //this is bad as we can't gurranty wait is long enough (or too long and cause performance)
        setTimeout(() => {
            console.log('delayed cb !!!!!!!!!!!!!!!!!!!!')
            cb();
        }, 1000);
        */
    }
}


function getConsumer() {
    return new stream.Writable({
        objectMode: true,
        write(chunk, enc, cb) {
            console.log(`======> Finish chunk`, chunk);
            setTimeout(() => {
                cb();
            }, 100);
        }
    })
}

function getAry() {
    const res = [];
    for (let i = 0; i < 100; i++) res.push(i);    
    return res;
}

async function test() {
    await pipelineAsync(
        stream.Readable.from(getAry())
        , new MyTransform()
        , getConsumer());


    console.log('all produced');
    
}

test();