📦 Test Structure

test(name,function,timeout)

🧿 test.only() :- just run the test file

🧿 test.skip() :- just skip the test file

📁-01. First test --> App.test.tsx

import {render, screen} from '@testing-library/react';
import App from './App'

test('render learn react link',()=>{
    render(<App/>);
    const linkElement =screen.getByText(/learn react/i);
    expect(linkElement).toBeInTheDocument();
})

🐘 By default jest is install inside

node_modules/react-scripts/package.json 

📦 Project setup

node --version
git --version
npx create-react-app . --template typescript
npm start

To Test the File run the command in the terminal

npm test

🧿 JEST WATCH MODE

    › Press a to run all tests.
    › Press f to run only failed tests.
    › Press o to only run tests related to changed files.
    › Press q to quit watch mode.
    › Press p to filter by a filename regex pattern.
    › Press t to filter by a test name regex pattern.
    › Press Enter to trigger a test run.

🧿 14. Code Coverage inside the package.json in "scripts"part

npm i --save-dev istanbul

"coverage": "npm test -- --coverage --watchAll"
"jest": {
    "collectCoverageFrom": [
    "src/**/*.{js,jsx,ts,tsx}"
    ],
    "coverageThreshold": {
    "global": {
        "branches": 80,
        "functions": 80,
        "lines": 80,
        "statement": -10
    }
    }
},

🧿 15. Assertions:

Writing values that meet certain conditions