test/parallel/test-stream-transform-callback-twice.js

'use strict';
const common = require('../common');
const { Transform } = require('stream');
const stream = new Transform({
  transform(chunk, enc, cb) { cb(); cb(); }
});

stream.on('error', common.expectsError({
  type: Error,
  message: 'Callback called multiple times',
  code: 'ERR_MULTIPLE_CALLBACK'
}));

stream.write('foo');