fix: remove stream.emit('close') on stream end

[Ivan-Baranov]

On node v18+ stream.emit('close') produce Error: Premature close

at new NodeError (node:internal/errors:405:5)
at Readable.onclose (node:internal/streams/end-of-stream:154:30)
at Readable.emit (node:events:514:28)

[wellwelwel]

Hi, @Ivan-Baranov 🙋🏻‍♂️

The CI failure comes from stream/promises that is missing on Node 14.

---

Instead:

if (process.versions.node.split(".", 1)[0] <= 14) {
  stream.emit('close'); // notify readers that query has completed
}

An alternative could be to use stream/promises as callback, for example:

const { finished } = require('stream');

const rowsStreamForAwait = [];
function testStreamForAwait(callback) {
  const stream = connection.execute('SELECT * FROM announcements').stream();
  stream.on('data', row => {
    rowsStreamForAwait.push(row);
  });
  stream.on('end', () => {
    callback(null);
  });
  stream.on('error', err => {
    callback(err);
  });
}
testStreamForAwait(err => {
  if (err) {
    throw err;
  }
});


const rowsStreamFinished = [];
function testStreamFinished(callback) {
  const stream = connection.execute('SELECT * FROM announcements').stream();
  stream.on('result', row => {
    rowsStreamFinished.push(row);
  });
  finished(stream, err => {
    callback(err);
  });
}
testStreamFinished(err => {
  if (err) {
    throw err;
  }
});

process.on('exit', () => {
  assert.deepEqual(rows, rowsStreamForAwait);
  assert.deepEqual(rows, rowsStreamFinished);
});

---

Also (just a small tip), if you're familiar with Docker, you can test locally any version of MySQL and NodeJS with a simple docker-compose.yml 🐳

version: '3.9'

services:
  mysql2:
    image: node:14
    working_dir: /usr/app
    volumes:
      - ./path-to-mysql2:/usr/app:ro
    command: npm run test
    environment:
      MYSQL_HOST: db
      use-compression: 0
      use-tls: 0
    depends_on:
      db:
        condition: service_healthy

  db:
    image: mysql:5.7
    platform: linux/amd64
    restart: always
    environment:
      MYSQL_DATABASE: 'test'
      MYSQL_ALLOW_EMPTY_PASSWORD: 'yes'
    healthcheck:
      test: ['CMD', 'mysqladmin', 'ping', '-h', 'localhost', '-u', 'root']
      interval: 10s
      timeout: 5s
      retries: 5

Then, run docker compose up and wait for the last log as "exited with code 0" 🧙🏻✨

[Ivan-Baranov]

I want to show error in node 18+, then used await finished(stream) or for await(let row of stream)