NPM install list:

jest babel-preset-env babel-preset-react react react-dom enzyme enzyme-adapter-react-16 react-test-renderer

• for basic JS testing: jest
• to use babel: babel-preset-env
• to use react (in jest files): babel-preset-react react react-dom
• to use enzyme: enzyme enzyme-adapter-react-16
• for snapshots: react-test-renderer

update test scripts in package.json:

  "scripts": {
    "test": "jest",
    "test_watch": "jest --watch"
  }