What I'm Working On

I'm attempting to write a Transform stream that will be used as part of a process that reads data from an HTTP API (Salesforce), transforms each resource into a standard internal data structure, and then sends the transformed data to be indexed by Elasticsearch.

My Problem

I've written a simple Transform stream, but it appears to be swallowing data, instead of passing it through.

Here's my class AdapterStream

const { Transform } = require('stream')

class AdapterStream extends Transform {
  constructor (adapter) {
    super({objectMode: true})
    // adapter is a function that contains the transform logic
    this.adapter = adapter
  }

  _transform (chunk, _encoding, callback) {
    this.push(this.adapter(chunk))
    callback()
  }
}

module.exports = AdapterStream

Here's how I'm using it

// query is an EventEmitter (https://jsforce.github.io/document/#query)
query.run({autoFetch: true, maxFetch: 10})
     .pipe(transform)
     .pipe(process.stdout)

What I expect to happen

I expect to see the transformed data in my terminal window.

What is actually happening

Nothing is printed in my terminal window

Things I've Tried

Writing to a file

query.run({autoFetch: true, maxFetch: 10})
     .pipe(transform)
     .pipe(fs.createWriteStream('./test.json'))

This creates the file ./test.json as expected, but it is empty.

Subscribing to events

query.run({autoFetch: true, maxFetch: 10})
     .pipe(transform)

transform.on('readable', () => { console.log(transform.read()) })

This does what I expected .pipe(process.stdout) to do: print the transformed records to the console.

My question is, why doesn't pipe() do what I'm expecting it to do? There must be something simple that I'm missing.