AVA Shared Worker utils

create-worker.js

const createDebug = require('debug')
const { serializeError } = require('serialize-error')

const receiveCommands = async (main, commands, debug) => {
  for await (const message of main.subscribe()) {
    if (message.data == null || typeof message.data.type !== 'string') {
      debug('unexpected message', { message })
      continue
    }
    const { type, payload } = message.data
    const data = {}
    debug('invoking command', { type, payload })
    try {
      const result = await commands[type](payload)
      debug('command succeeded', { type, result })
      data.result = result
    } catch (error) {
      debug('command failed', { type, error })
      data.error = serializeError(error)
    } finally {
      debug('acknowledging command', { type, data })
      try {
        await message.reply(data)
        debug('acknowledgment succeeded', { type })
      } catch (error) {
        debug('acknowledgment failed', { type, error })
      }
    }
  }
}

const createWorker = (id, init, dispose, commands) => async ({
  negotiateProtocol
}) => {
  const debug = createDebug(`browsertest:${id}:proc`)
  const main = negotiateProtocol(['experimental'])
  await init()
  main.ready()
  const commandsWithDispose = {
    ...commands,
    _dispose: async () => {
      debug('disposing')
      try {
        await dispose()
        debug('disposal succeeded')
      } catch (error) {
        debug('disposal failed', { error })
      }
    }
  }
  await receiveCommands(main, commandsWithDispose, debug)
}

module.exports = createWorker

register-worker.js

const createDebug = require('debug')
const { registerSharedWorker } = require('ava/plugin')
const sendCommand = require('./send-command')

const registerWorker = (id, filename) => {
  const worker = registerSharedWorker({
    filename,
    supportedProtocols: ['experimental'],
    teardown: async () => {
      await sendCommand(worker, '_dispose')
    }
  })
  worker._debug = createDebug(`browsertest:${id}:remote`)
  return worker
}

module.exports = registerWorker

send-command.js

const { deserializeError } = require('serialize-error')

const sendCommand = async (worker, type, payload = {}) => {
  const debug = worker._debug
  debug('sending command', { type, payload })
  const { replies } = await worker.publish({ type, payload })
  debug('sent command', { type })
  const iter = await replies().next()
  const {
    data: { result, error }
  } = iter.value
  debug('got command response', { type, result, error })
  if (error != null) {
    throw deserializeError(error)
  }
  return result
}

module.exports = sendCommand