Unit testing components in Javascript Storybook

22 Sep 2023

storybook

In modern web development, building and testing components is an essential part of the process. Unit testing helps ensure that individual components of your application function correctly and independently. One popular tool for developing and testing components in JavaScript is Storybook.

What is Storybook?

Storybook is an open-source tool that allows you to develop, test, and document components in isolation. It allows you to view components in different states and scenarios without having to navigate through your entire application. This makes it easier to build and test components in isolation, improving development speed and product quality.

Setting up Storybook with Testing

To get started with testing components in Storybook, follow these steps:

Install Storybook globally using the following command:
```
npm install -g @storybook/cli
```
Create a new Storybook project inside your existing JavaScript project:
```
npx -p @storybook/cli sb init
```
Configure your project’s testing framework, such as Jest, to work with Storybook.

For example, if you’re using Jest, you can install the necessary dependencies:
```
npm install --save-dev @storybook/addon-storyshots jest
```
Create a test file for your components. Typically, you would create a *.test.js file for each component.

Write unit tests for your components, using assertions to check their behavior.

import { render, screen } from "@testing-library/react";
import MyComponent from "./MyComponent";

test("renders MyComponent correctly", () => {
  render(<MyComponent />);
  const element = screen.getByText("Hello World!");
  expect(element).toBeInTheDocument();
});

Add a new story file for your component inside the Storybook’s stories directory.

import React from "react";
import MyComponent from "./MyComponent";

export default {
  title: "Components/MyComponent",
  component: MyComponent,
};

export const Default = (args) => <MyComponent {...args} />;

Run your tests and see the results:
```
npm test
```

Now you have a setup where you can write and run tests for your components within Storybook.

Conclusion

Unit testing components is crucial for ensuring the stability and functionality of your JavaScript applications. Storybook provides an excellent environment for developing and testing components in isolation, making it easier to catch bugs and build high-quality components.

With the steps outlined above, you can set up Storybook and integrate it with your testing framework to write unit tests for your components. Happy testing and happy component development!

#javascript #storybook #unittesting