Setting up Jest in ESM projects

This is applicable for Jest 28+. As of writing, it is unreleased.

yarn add --dev jest@next

package.json:

{
  "scripts": {
    "jest": "^28.0.0-alpha.7"
  }
}

jest.config.js:

module.exports = {
  transform: {},
  testMatch: ['**/*.test.mjs'],
  moduleFileExtensions: ['js', 'mjs'],
}