Jests Basic

npm install --save-dev jest
//json
{
  "scripts": {
    "test": "jest"
  }
}
npm test


//mock dom
npm install --save-dev jest-environment-jsdom
/**
 * @jest-environment jsdom
 */


//jest-localstorage-mock
npm i --save-dev jest-localstorage-mock
{
  "name": "to-do-list",
  "version": "1.0.0",
  "description": "<a name=\"To Do List\"></a>",
  "private": true,
  "jest": {
    "resetMocks": false,
    "setupFiles": [
      "jest-localstorage-mock"
    ]
  },
  "scripts": {
    "test": "jest",...
    
//Babel
npm install --save-dev @babel/plugin-transform-modules-commonjs
//create a new file in the project root directory called: .babelrc with the following code in it:
{
  "env": {
    "test": {
      "plugins": ["@babel/plugin-transform-modules-commonjs"]
    }
  }
}

    
//REACT
npm install --save-dev react-test-renderer
jest --updateSnapshot
//auto complete : 
npm install @types/jest