How to use Jest In Javascript
The Jest is a widely used testing framework developed by Facebook. It is popular for testing React applications but can be used for any JavaScript project. Jest is known for its ease of use, powerful features, and comprehensive documentation.
Syntax:
test('description of the test', () => {
// arrange
// act
// assert
});
Let’s consider a simple function that adds two numbers and we will write a unit test for it using Jest.
Function Code:
// math.js
function add(a, b) {
return a + b;
}
module.exports = add;
Test Code:
// math.test.js
const add = require('./math');
test('adds 1 + 2 to equal 3', () => {
expect(add(1, 2)).toBe(3);
});
Running the Tests: To run the tests, you need to the have Jest installed. We can install it using npm.
npm install --save-dev jest
Then, add a script to your package.json to the run Jest:
"scripts": { "test": "jest"}
Now you can run your tests using:
npm test
How to Start Unit Testing to a JavaScript Code?
Unit testing is a crucial part of software development that helps ensure individual parts of the code work correctly. For JavaScript, unit testing can be especially valuable given the dynamic nature of the language. This guide will introduce you to the two popular approaches to unit testing in JavaScript providing the descriptions, syntax, and example implementation code.
These are the following approaches:
Table of Content
- Using Jest
- Using Mocha and Chai