Jest - Configuring Jest

Jest is a delightful JavaScript Testing Framework with a focus on simplicity. It works with projects using: Babel, TypeScript, Node, React, Angular, Vue and more!

Install:

npm i jest -D

Setup:

package.json

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

By default, Jest only supports standard JavaScript syntax. Once you want to import a function, you have to use 'require'

Such as:

const {plus, subtract} = require('./calculator.js')

If you are using 'import', there is an error as below:

If you want to use 'import', you have to install the following dependencies:

    "@babel/core": "^7.17.4""@babel/preset-env": "^7.16.11"

Then we need to configure the .babelrc

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

Also if there is TypeScript In your project, you have to add the babel for typescript

npm i -D @babel/preset-typescript

.babelrc

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