babel-jest does not transpile import/export in node_modules when Babel 7 is used

🐛 Bug Report

I started getting the dreaded SyntaxError: Unexpected token import error again for lodash-es. And I spent hours debugging it, because I already had .babelrc and package.json:jest configured properly ("modules": "commonjs", a jest.transform for babel-jest, and transformIgnorePatterns set to not ignore node_modules/lodash-es).

After a lot of debugging and a little searching, it appears that Babel 7 has stopped using the project’s .babelrc code in node_modules. This means that all the previous suggestions to just tell transformIgnorePatterns to transpile certain packages in node_modules and set "modules": "commonjs" in the test env to make WebPack import work with jest no longer work.

To Reproduce

Steps to reproduce the behavior:

• Import an es-modules using library like lodash-es into your project
• Write a Jest test that imports the file you import the es-modules using package
• Setup a recent version of Babel 7
• Configure .babelrc to use the env preset to transpile ES6 modules to CommonJS
• Configure Jest to transform .js files with babel-jest and transformIgnorePatterns to not ignore the es-modules using package

Expected behavior

When babel-jest is used to transpile ES-modules using packages like lodash-es it should transpile the imports to CommonJS so they work with Jest.

Practically I believe it should be sufficient to add transform-modules-commonjs to the plugins list that babel-jest uses when the filename is a node_modules file and Babel 7 is used. This would also fix the fact that it’s not good practice for the project’s .babelrc (which may also include plugins for non-standard things like JSX and flow) to be used just to transpile ES6 / modules code in packages.

Link to repl or repo (highly encouraged)

https://gist.github.com/dantman/820f6232acc6f53bd1e57d21b09e1f89

Run npx envinfo --preset jest

Paste the results here:

  System:
    OS: macOS Sierra 10.12.6
    CPU: x64 Intel(R) Core(TM) i5-7267U CPU @ 3.10GHz
  Binaries:
    Node: 9.11.1 - ~/.nvm/versions/node/v9.11.1/bin/node
    Yarn: 1.6.0 - /usr/local/bin/yarn
    npm: 5.6.0 - ~/.nvm/versions/node/v9.11.1/bin/npm
  npmPackages:
    jest: ^22.4.4 => 22.4.4

[austinkelleher]

For the record, I was able to fix the issue of my module in the node_modules folder not compiling properly by:

1. Changing the filename .babelrc to babel.config.js and module.exports the config object
2. Adding transformIgnorePatterns to my Jest config:

"transformIgnorePatterns": [
  // Change MODULE_NAME_HERE to your module that isn't being compiled
  "/node_modules/(?!MODULE_NAME_HERE).+\\.js$"
]

[norbertkeri]

Renaming .babelrc to babel.config.js worked for me