rescript+jest+es6.md

1. Install these packages:

yarn install --dev @babel/core @babel/preset-env jest babel-jest

2. Add babel.config.js (exactly babel.config.js, not .babelrc, not .babelrc.json etc):

module.exports = {
  presets: ["@babel/preset-env"],
};

3. Add jest.config.js:

module.exports = {
  testEnvironment: "node",
  testRegex: "tests/.*\\.res\\.js$", // optional, defines custom tests location
  transformIgnorePatterns: [
    "/node_modules/(?!rescript|ALL-RESCRIPT-DEPS|THAT-APPEAR-IN-TESTS).+\\.res\\.js$",
  ]
};

4. Run jest and pray