Storybook Visual Regression boilerplate

Storybook boilerplate which combines ReactJS, Typescript and Visual Regression testing using WebDriverIO

• Storybook Visual Regression boilerplate
  • Motivation
  • Getting started
  • How to create a React Component along with a Story
    • Structure
    • Component template
    • Creating a Story
  • Visual Regression Testing
    • Run selenium Docker image
    • Create entry test file
    • Run the visual regression test
    • Debug visual regression test
      • Mac
  • Contributors ✨

Motivation

As we all know ReactJS continues to lead the way as far as being the most widely used Javascript library and in the opinion of many, the most powerful. If you combine ReactJS with Storybook and visual regression testing from Webdriver IO it is possible to create a design system and a custom component library that can be safely reused between products and/or other teams. Sometimes when sharing a UI library among a large group or multiple teams we run in to issues when one person makes what might seem to be trivial or small change to a shared component. These changes might cause issues for other users who are using the same component in another place. Often times small modifications or changes can slip through code reviews too. With this boilerplate we incorporated the ability to run visual regression testing on each component. This allows developers to see even the slightest of changes and decide if it is acceptible or not before commiting to the changes.

Getting started

To run this project please follow these steps:

1. Make sure you have Docker & NodeJS installed on your machine
2. Pull the standalone-chrome-debug or standalone-firefox-debug docker image
3. Clone this repo
4. Install dependencies

npm install

5. Start storybook with development mode

npm run storybook

How to create a React Component along with a Story

Structure

my-react-component
  |-- stories/
      |-- vr-test/
          |-- index.spec.ts
      |-- story-1.story.tsx
      |-- story-2.story.tsx
      |-- story-3.story.tsx
  |-- index.tsx
  |-- style.less

Component template

src/components/button/index.tsx

import * as React from 'react';
import * as style from './style.less';

export class Button extends React.Component<Props> {
  public render(): JSX.Element {
    const className = [style.container, style[this.props.size || '']];

    return (
      <button onClick={this.props.onClick} id="button" className={className.join(' ')}>
        {this.props.children}
      </button>
    );
  }
}

export type Props = DataProps & EventProps;

interface DataProps {
  /** Children node */
  children: string | React.ReactNode;
  /** Size of button */
  size?: 'small' | 'medium' | 'large';
}

interface EventProps {
  /** Click event */
  onClick?: (e: React.MouseEvent<HTMLElement>) => void;
}

src/components/button/style.less

.container {
  background: blue;
  width: 100%;
}

.small {
  background: yellow;
}

.medium {
  background: green;
}

.large {
  background: red;
}

Creating a Story

File name pattern: src/components/<component-name>/stories/<test-case-name>.story.tsx

Example:

src/components/button/stories/large.story.tsx

import { Props } from '..'; // import the Props from the component

export const test: Props = {
  children: 'large size',
  size: 'large',
};

src/components/button/stories/small.story.tsx

import { Props } from '..'; // import the Props from the component

export const test: Props = {
  children: 'small size',
  size: 'small',
};

Visual Regression Testing

This type of testing produces snapshots of the component as *.png files.

For example:

Here is a visual regression test for button component

button with large size

button with medium size

button with small size

Here is a visual regression test for text component

text with black background

text with red background

After completing the React component, to run the visual regression test, you need to do a little set up.

Run selenium Docker image

Make sure to start Docker

To run Selenium of web drivers, you can choose either running Docker commands

docker run -d -p 4444:4444 -p 5900:5900 selenium/standalone-chrome-debug

or using docker-compose.yml

docker-compose up

Advance: You can customize export ports by arguments if default ports are already allocated

Example

CHROME_MAIN_PORT=6666 CHROME_DEBUG_PORT=5909 docker-compose up

Create entry test file

Create the file src/components/<component-name>/stories/vr-test/index.spec.ts with code below

import { VisualRegressionTest } from 'lib/test/visual-regression-test';
import * as style from '../../style.less';

new VisualRegressionTest(__dirname, style.container).run();

style.container is the className wrapped around the component

Run the visual regression test

To run the visual regression test, make sure your storybook started.

Desktop

npm run test:chrome src/components/<component-name>/stories/vr-test/index.spec.ts

Smartphone

npm run test:chrome:smartphone src/components/<component-name>/stories/vr-test/index.spec.ts

Both Desktop and Smartphone

npm test src/components/<component-name>/stories/vr-test/index.spec.ts

Run all tests

npm test

Debug visual regression test

Mac

Screen Sharing

To debug visual regression testing

1. Open the Screen Sharing

chrome

Hostname: `YOUR_MACHINE_IP`:5900
Password: secret

2. Run test
3. Navigate to Screen Sharing to see the step by step for running the test

Contributors ✨

Dzung Nguyen 📖 💻 🤔 👀 🐛

Hoc Nguyen 💻 🤔 👀 🐛

Khoa Do 💻 👀 🐛

Nguyen Van Hao 💻 📖

Ben Lee 📖 💻