How to transform module after ordinary transform h

问题:

Testing React components with jest. Some of these components make use of OpenLayers (ol package v5.2.0). In ol package v4 I applied transformIgnorePatterns to have the ol package transformed:

"jest": {
    "transformIgnorePatterns": [
         "node_modules/(?!(ol)/)"
    ],
    (...)
}

Now I get the following error when running NODE_ENV=test jest:

(...)
(...)/node_modules/ol/index.js:5
export {default as AssertionError} from './AssertionError.js';
^^^^^^

SyntaxError: Unexpected token export

  14 |     let map = new Map({
  15 |       layers: options.layers,
> 16 |       target: 'map',
     |           ^
  17 |       view: options.view,
  18 |       controls: options.controls
  19 |     });

I have applied the following presets and plugins in .babelrc:

"presets": [
   ["@babel/preset-env", {
     "modules": false
    }
   ],
   "@babel/preset-react"
],
"plugins": [
    "lodash",
    ["@babel/plugin-transform-runtime", {
      "corejs": 2,
      "helpers": true,
      "regenerator": true,
      "useESModules": false
    }
  ],
  "@babel/plugin-transform-modules-commonjs",
  "@babel/transform-arrow-functions",
  "@babel/plugin-syntax-dynamic-import",
  "@babel/plugin-syntax-import-meta",
  ["@babel/plugin-proposal-class-properties", {"loose": false}],
  "@babel/plugin-proposal-json-strings"],
"env": {
    "production": {},
    "development": {},
    "test": {
      "presets": [
        ["@babel/preset-env"],
        "@babel/preset-react"
      ]
    }
  }

A similar problem is solved when building the application by applying the global-transform option (https://github.com/browserify/browserify#usage) cf. this issue thread: https://github.com/openlayers/openlayers/issues/8497.

$ browserify -g [ babelify --presets [ \"@babel/preset-env\" ] --ignore [ \"//node_modules/(?!ol/)/\" ] ] ./src/index.js -o ./public/js/bundle.js

I want to apply a similar transformation to the ol module but unsure on how to approach it. The transformIgnorePatterns used to solve this problem cf. https://github.com/facebook/jest/issues/2550

回答1:

The error no longer occurs if I put the contents of .babelrc into babel.config.js in the root of the project.

module.exports = {
    (...)
};

cf.

• https://github.com/facebook/jest/issues/6229
• https://github.com/facebook/jest/issues/6053#issuecomment-383632515

side effect - TypeError: $export is not a function when loading the bundle built via browserify/babelify, but I guess it is a configuration problem.

Edit: Side effect was solved for me by changing the options for the plugin "@babel/plugin-transform-runtime" to:

{
  "corejs": false,
  "helpers": false,
  "regenerator": true,
  "useESModules": false
}

cf. https://stackoverflow.com/a/39502362/3798151 and installing @babel/runtime cf. https://babeljs.io/docs/en/babel-plugin-transform-runtime