node/test/parallel/test-stream-once-readable-pipe.js

'use strict';

const common = require('../common');
const assert = require('assert');
const { Readable, Writable } = require('stream');

// This test ensures that if have 'readable' listener
// on Readable instance it will not disrupt the pipe.

{
  let receivedData = '';
  const w = new Writable({
    write: (chunk, env, callback) => {
      receivedData += chunk;
      callback();
    },
  });

  const data = ['foo', 'bar', 'baz'];
  const r = new Readable({
    read: () => {},
  });

  r.once('readable', common.mustCall());

  r.pipe(w);
  r.push(data[0]);
  r.push(data[1]);
  r.push(data[2]);
  r.push(null);

  w.on('finish', common.mustCall(() => {
    assert.strictEqual(receivedData, data.join(''));
  }));
}

{
  let receivedData = '';
  const w = new Writable({
    write: (chunk, env, callback) => {
      receivedData += chunk;
      callback();
    },
  });

  const data = ['foo', 'bar', 'baz'];
  const r = new Readable({
    read: () => {},
  });

  r.pipe(w);
  r.push(data[0]);
  r.push(data[1]);
  r.push(data[2]);
  r.push(null);
  r.once('readable', common.mustCall());

  w.on('finish', common.mustCall(() => {
    assert.strictEqual(receivedData, data.join(''));
  }));
}