myapp/node_modules/babel-jest/README.md

babel-jest

Babel jest plugin

Usage

If you are already using jest-cli, just add babel-jest and it will automatically compile JavaScript code using Babel.

yarn add --dev babel-jest @babel/core

If you would like to write your own preprocessor, uninstall and delete babel-jest and set the config.transform option to your preprocessor.

Setup

Note: this step is only required if you are using babel-jest with additional code preprocessors.

To explicitly define babel-jest as a transformer for your JavaScript code, map .js files to the babel-jest module. Typescript files are also supported.

"transform": {
  "^.+\\.[t|j]sx?$": "babel-jest"
},