Component Testing In React With Jest And Testing Library

In today’s world, many websites and apps are built using React. React helps developers make websites. The websites are fast. They are easy to use. They are fun to look at. When we build a website, we also test it. We check if everything works. Testing makes sure everything works fine. One very useful way to test is called component testing.

In this blog, we will learn about component testing. We will see how to do it using Jest and Testing Library. We will also learn why it is important. If you are learning software testing, you can join Software Testing Online Classes. They help you improve your skills. You can also learn more tools and techniques.

What is Component Testing?

A website has many small parts. These small parts are called components in React. For example, a button is a component. A search bar is also a component. Component testing means checking each small part one by one. We test if the button works. We test if the search bar gives results. When each part works well, the full website will work better.

Why Use Jest and Testing Library?

Jest is a tool made by Facebook. It is used to test JavaScript code. It works very well with React. It is fast and simple.

React Testing Library helps us test React components. It checks how users use the website. It is good because it looks at the website like a real user. We click buttons. We type in input fields. It feels natural.

Tools Comparison Table

Steps to Test a React Component

Let us see how to test a button component in React. We will use Jest and Testing Library.

Here is an example code:

// Button.js

import React, { useState } from 'react';

function Button() {

  const [count, setCount] = useState(0);

  return (

    <div>

      <p>You clicked {count} times</p>

      <button onClick={() => setCount(count + 1)}>Click Me</button>

    </div>

  );

}

export default Button;

// Button.test.js

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

import Button from './Button';

test('Button clicks increase count', () => {

  render(<Button />;

  const button = screen.getByText('Click Me');

  fireEvent.click(button);

  expect(screen.getByText('You clicked 1 times')).toBeInTheDocument();

});

Why Component Testing is Useful?

Example

Imagine a shopping website. It has a product list. Each product is a small component. There is a cart button. There is a search box. We can test each part using Jest and Testing Library. We can check if the product list loads. We can check if the cart button adds items. We can test if the search box gives the right items.

Test Cases for a Product Component

Link to Data Flow Testing

When we test how data moves inside the app, we use Data Flow Testing in Software Testing. For example, when we type something in a form and click submit, the data flows from the input box to the server. We can test if this flow is working. In React, we can write test cases to check this. Jest and Testing Library can be used for this too.

Cost of Learning

Some students ask about fees. If you are in India and want to learn software testing, you can check the Software Testing Course Fees in Noida. Many training centers offer good courses. They also give practice projects and help with jobs.

Now, let’s talk about Noida! It’s a busy city near Delhi. There are lots of IT companies and offices here. People come to work, study, and learn new skills. The buildings are big, and there are lots of tech parks. If you learn software testing in Noida, you might even get a job in the same city! It's like going to school and maybe getting your first job nearby.

Tips to Remember

Conclusion

Component testing is very important in React. Jest and Testing Library make it simple. They are fast and help us find bugs easily. With practice, you will get better at testing. If you want to learn more, try small projects first. Then move to big apps. Testing makes your code strong and your users happy.