Configure Jest to use it with NodeJS ECMAScript Modules

1. Initialize your application:

     npm init
   

2. To use ES modules, add type: "module" to package.json file.

3. Install Jest

    npm i jest
   

4. Initialize Jest

     npm init jest@latest
   

5. In jest.config.mjs file: de-comment transform key and assign it a value like transform: { "^.+\\.js$": "babel-jest" }. Just be aware that the rejex will depend on the file extensions on your project.

6. Install babel

    npm i @babel/core @babel/node @babel/preset-env
   

7. Configure babel by creating .babelrc file in the root folder.

8. Inside .babelrc file add:

    {
        "presets": [["@babel/preset-env", { "targets": { "node": "current" } }]]
    }
   

To start running your tests:

1. add the test script to scripts inside package.json file

     "scripts": {
        "test": "jest"
      },
   

2. run the script

    npm run test