jest-esm-experiments

This project is a minimal reproducible bug of the problem I encountered in my other project topheman/webrtc-experiments.

git clone

1) Due to following error:

TypeError: Jest: a transform must export a `process` function.

Downgrading to esm@3.1.0 - source

2) Not working even with esm setup as loader for jest

Basic jest.config.js:

module.exports = {
  transform: {
    "\\.m?jsx?$": "esm"
  },
  moduleNameMapper: {
    "^anotherRoot/(.*)$": "<rootDir>/lib/anotherRoot/$1"
  },
  transformIgnorePatterns: []
};

When you run npm test, you fill get the following error:

 PASS  src/common.test.js
 FAIL  src/string.test.js
  ● Test suite failed to run

    TypeError: Cannot read property 'next' of undefined

      at Object.n.(anonymous function) (node_modules/esm/esm.js:1:1796)

 FAIL  src/math.test.js
  ● Test suite failed to run

    TypeError: Cannot read property 'next' of undefined

      at Object.n.(anonymous function) (node_modules/esm/esm.js:1:1796)

Test Suites: 2 failed, 1 passed, 3 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.457s
Ran all test suites

This might be due to the fact that src/common.js file is being imported:

• directly in one of the tests
• indirectly by the components I'm testing in the 2 other tests