async tests fail after upgrading from 21.x to 22.x

Do you want to request a feature or report a bug?

Bug.

Problem

After upgrading Jest from 21.2.1 to 22.4.2, async tests always fail with error ReferenceError: regeneratorRuntime is not defined. Steps to reproduce:

1. git clone https://github.com/iwinux/jest-async-bug.git
2. yarn install && yarn jest

If I revert Jest back to 21.2.1, it runs without error.

Environment

• OS: both macOS / Linux
• Node v8.9.1
• Yarn v1.3.2
• Jest v22.4.2

Jest Config

// jest.config.js
module.exports = {
  browser: true,
  moduleDirectories: ['<rootDir>/src', '<rootDir>/node_modules'],
  testMatch: ['<rootDir>/tests/**/*.spec.js'],
  testPathIgnorePatterns: ['/node_modules/'],
  transform: {
    '^.+\\.jsx?$': '<rootDir>/babel-transform.js',
  },
  verbose: true,
}

// babel-transform.js
const fs = require('fs')
const path = require('path')

const { createTransformer } = require('babel-jest')

function makeConfig() {
  const filePath = path.resolve(__dirname, './.babelrc')
  const rawContent = fs.readFileSync(filePath, { encoding: 'utf-8' })
  const config = JSON.parse(rawContent)
  config.presets[0][1].modules = 'commonjs'
  return config
}

module.exports = createTransformer(makeConfig())

// .babelrc
{
  "presets": [
    ["env", {
      "debug": false,
      "modules": false,
      "targets": {
        "browsers": [
          "last 2 versions",
          "Chrome >= 45",
          "Firefox >= 50",
          "IE >= 11",
          "Safari >= 10"
        ]
      },
      "useBuiltIns": true
    }]
  ],
  "comments": true,
  "plugins": [
    "syntax-dynamic-import",
    "transform-class-properties",
    "transform-object-rest-spread"
  ]
}

[iwinux]

OK, adding setupFiles: ['<rootDir>/node_modules/regenerator-runtime/runtime'] to jest.config.js works. Thanks!

Should I close this issue now?

[thymikee]

Well that’s weird, it shouldn’t work at all on v21 too, because you’re using custom transformer (do you need it? maybe try removing “transform” option and see if the default one suits you) and possibly not loading regenerator-runtime. You need to bootstrap it before running async tests, e.g. inside setupFiles:

"setupFiles" ["<rootDir>/node_modules/regenerator-runtime/runtime"]