`regeneratorRuntime` is not defined when running Jest test

Question

The title pretty much explains what I'm facing. I'm trying to test a React component that has some state, and I attempt to provide my store to the component in order to get what it needs. When I run the test of the component using Jest, I get the following error:

ReferenceError: regeneratorRuntime is not defined

I've determined through some reading that this is caused by babel-polyfill or regenerator-runtime not being applied correctly to Jest. However, I've tried installing both of those packages and re-running with no change in results. After reading the Jest Github issues page (Remove auto-inclusion of babel-polyfill #2755), I found out that babel-polyfill is not included automatically by Jest as of version 19. My manual installation of that package should have fixed the issue, but it did not. I've included some of the files that I think are relevant

.babelrc:

{
  "presets": ["es2015", "react", "stage-2"],
  "env": {
    "development": {
      "plugins": [
        ["react-transform", {
          "transforms": [{
            "transform": "react-transform-hmr",
            "imports": ["react"],
            "locals": ["module"]
          }]
        }]
      ]
    }
  }
}

jest.config:

{
    "transform": {
        "^.+\\.(js|jsx)$": "<rootDir>/node_modules/webpack-babel-jest",
        ".*\\.(vue)$": "<rootDir>/node_modules/jest-vue-preprocessor",
        ".*": "babel-jest"
    },
    "moduleNameMapper": {
        "\\.(jpg|jpeg|css|scss|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$": "<rootDir>/__tests__/__mocks__/fileMock.js",
        ".*\\.(vue)$": "vue/dist/vue.js"
    },
    "testPathIgnorePatterns": ["type_parser.spec.js", 
                               "<rootDir>/__tests__/__mocks__/",
                               "__tests__/unit/core/util/type_parser.js",
                               "__tests__/GitlabLoader.test.js"
                               ]
}

package.json:

{
  "name": "my_project",
  "version": "0.2.0",
  "description": "My Project",
  "scripts": {
    "clean:build": "node ./bin/clean.js createdir",
    "build:html": "node ./bin/buildHtml.js",
    "deployProduction": "node ./bin/deployProduction.js",
    "start": "webpack-dev-server --config ./config/webpack.config.dev.js --hot --inline --progress",
    "serve": "npm run deployProduction&& supervisor --watch ./production-copy src/js/server",
    "prebuild": "npm run clean:build",
    "postbuild": "node ./bin/postBuild.js",
    "rebuild-win": "set BUILD_TYPE=preview& npm run prebuild & npm run build-win & npm run serve",
    "build": "set BUILD_TYPE=final& npm run prebuild & npm run build-win",
    "deploy": "npm run build & npm run serve",
    "build-win": "set NODE_ENV=production & npm run element-build & npm run build-doc & npm run build:html &  webpack -p --config ./config/webpack.config.prod.js --json > webpack.log.json & npm run postbuild",
    "lint": "eslint config src/js/**/*.js",
    "jscs": "jscs src/js/",
    "test": "jest --no-cache --verbose --config=./__tests__/jest.config",
    "test:watch": "npm run test -- --watch",
    "element-init": "node node_modules/element-theme/bin/element-theme -i src/js/core/ui/element-theme.css",
    "element-build": "node node_modules/element-theme/bin/element-theme -c src/js/core/ui/element-theme.css -o src/js/core/ui/element-theme ",
    "build-doc": "node bin/buildDoc.js ",
    "storybook": "start-storybook -p 9001 -c .storybook"
  },
  "repository": {
    "type": "git",
    "url": "my_url"
  },
  "license": "MIT",
  "bugs": {
    "url": "my_url"
  },
  "homepage": "my_homepage",
  "dependencies": {
    "autoprefixer": "^6.3.6",
    "axios": "^0.11.1",
    "babel-runtime": "^6.23.0",
    "babel-standalone": "^6.10.3",
    "bluebird": "^3.4.0",
    "brace": "^0.8.0",
    "browserify": "^13.0.1",
    "chai": "^3.5.0",
    "classnames": "2.2.3",
    "cls-bluebird": "^1.0.1",
    "codemirror": "^5.16.0",
    "connect-history-api-fallback": "^1.3.0",
    "continuation-local-storage": "^3.1.7",
    "dateformat": "^1.0.12",
    "diff": "^3.0.1",
    "element-theme": "^0.4.0",
    "element-ui": "^1.1.5",
    "express-history-api-fallback": "^2.0.0",
    "filedrop": "^2.0.0",
    "fs-extra": "^0.30.0",
    "history": "^2.0.2",
    "humps": "^1.0.0",
    "immutability-helper": "^2.1.1",
    "isomorphic-fetch": "^2.2.1",
    "json-loader": "^0.5.4",
    "jszip": "^3.0.0",
    "jszip-utils": "0.0.2",
    "material-ui": "^0.16.7",
    "materialize-css": "^0.97.6",
    "mocha": "^2.5.3",
    "moment": "^2.17.1",
    "normalizr": "^1.0.0",
    "raven-js": "^3.9.1",
    "react": "^15.0.1",
    "react-ace": "^3.5.0",
    "react-addons-update": "^15.4.2",
    "react-dom": "^15.0.1",
    "react-redux": "^4.4.5",
    "react-router": "^2.3.0",
    "react-router-redux": "^4.0.2",
    "redux": "^3.4.0",
    "redux-logger": "^2.6.1",
    "redux-saga": "^0.9.5",
    "request": "^2.72.0",
    "request-promise": "^3.0.0",
    "reselect": "^2.5.4",
    "save-as": "^0.1.7",
    "showdown": "^1.4.2",
    "three": "^0.79.0",
    "url-pattern": "^1.0.3",
    "vue": "^2.0.5",
    "vue-easy-slider": "^1.4.0",
    "vue-loader": "^9.8.1",
    "vue-router": "^2.0.1",
    "vue-slider-component": "^2.0.4",
    "walk": "^2.3.9"
  },
  "devDependencies": {
    "@kadira/storybook": "^2.35.3",
    "babel-core": "^6.7.6",
    "babel-eslint": "^6.1.0",
    "babel-jest": "^18.0.0",
    "babel-loader": "^6.0.2",
    "babel-plugin-react-transform": "^2.0.2",
    "babel-polyfill": "^6.23.0",
    "babel-preset-es2015": "^6.22.0",
    "babel-preset-es2016": "^6.22.0",
    "babel-preset-react": "^6.23.0",
    "babel-preset-stage-2": "^6.5.0",
    "babel-register": "^6.7.2",
    "chai": "3.5.0",
    "chai-jquery": "2.0.0",
    "cheerio": "0.20.0",
    "colors": "1.1.2",
    "concurrently": "^2.0.0",
    "copy-webpack-plugin": "2.1.1",
    "css-loader": "0.23.1",
    "element-theme-default": "^1.1.5",
    "enzyme": "^2.7.1",
    "eslint": "^2.13.1",
    "eslint-config-airbnb": "^9.0.1",
    "eslint-plugin-import": "^2.2.0",
    "eslint-plugin-jsx-a11y": "^4.0.0",
    "eslint-plugin-react": "^5.2.2",
    "express": "^4.13.4",
    "extract-text-webpack-plugin": "1.0.1",
    "file-loader": "0.8.5",
    "identity-obj-proxy": "^3.0.0",
    "jest": "^19.0.2",
    "jest-cli": "^18.1.0",
    "jest-css-modules": "^1.1.0",
    "jest-enzyme": "^2.1.2",
    "jest-vue-preprocessor": "^0.1.2",
    "jquery": "2.2.3",
    "jscs": "3.0.3",
    "jsdoc-to-markdown": "^2.0.0",
    "jsdom": "8.4.0",
    "json-loader": "^0.5.4",
    "mocha": "^2.4.5",
    "ncp": "^2.0.0",
    "node-sass": "3.7.0",
    "postcss-loader": "0.8.2",
    "react-addons-test-utils": "^15.4.2",
    "react-hot-loader": "1.3.0",
    "react-test-renderer": "^15.4.2",
    "react-transform-hmr": "^1.0.4",
    "redux-devtools": "^3.3.1",
    "redux-devtools-dock-monitor": "^1.1.1",
    "redux-devtools-log-monitor": "^1.0.11",
    "regenerator-runtime": "^0.10.3",
    "remotedev": "^0.1.2",
    "rimraf": "^2.5.2",
    "sass-loader": "3.2.0",
    "storybook-addon-material-ui": "^0.7.6",
    "style-loader": "0.13.1",
    "url-loader": "0.5.7",
    "vueify": "^9.4.0",
    "webpack": "^1.13.0",
    "webpack-babel-jest": "^1.0.4",
    "webpack-dev-middleware": "^1.6.1",
    "webpack-dev-server": "^1.16.3",
    "webpack-hot-middleware": "^2.10.0"
  }
}

Answer 1

In case you are using a setupTests.js file you can import regenerator-runtime from there:

// setupTests.js

import 'regenerator-runtime/runtime'
import Enzyme from 'enzyme'
import EnzymeAdapter from 'enzyme-adapter-react-16'

Enzyme.configure({
  adapter: new EnzymeAdapter()
})

 
Then you can import setupTests.js to every test file or better yet, in your package.json just add setupFilesAfterEnv to the jest config:

// package.json

{
  ...
  "dependencies": {
    ...
  },
  "devDependencies": {
    ...
  },
  "jest": {
    "setupFilesAfterEnv": ["./pathToYour/setupTests.js"] 
  }
}

 
Don't forget to install the regenerator-runtime package:

$ yarn add regenerator-runtime --dev

 
There is no need to import the complete babel-polyfill (or @babel/polyfill if Babel ≥ v.7.0.0) that btw has been deprecated in favor of directly including core-js/stable and regenerator-runtime/runtime.

Answer 2

While importing babel-polyfill into each test worked, the Updated jest docs (v24) suggests setting this in your babel config. If you do this you should no longer need to import babel-polyfill. (Personally, I was missing the targets option from my preset-env config).

// babel.config.js
module.exports = {
  presets: [
    [
      '@babel/preset-env',
      {
        targets: {
          node: 'current',
        },
      },
    ],
  ],
};

A word to the wise: specifying targets will override any browserslist config you have defined (that babel would otherwise use). So in a web project, you'll probably want to create a dynamic babel.config.js that is "jest-aware" so that you're only adding targets when it's a test environment. See the section titled "Making your Babel config jest-aware" in the jest docs.