Course Introduction

Introduction

Let's understand what this tool is all about.

What is Storybook? Better React UI Component Development

Storybook and Component Driven, Atomic Design in React

Let's learn about the installation process of Storybook.

How to Install Storybook and Add Stories to React Components

Let's learn about the very basics of Storybook stories

Intro to Storybook Component Story Format and args

Let's understand what Storybook decorators are and how to create them.

How to use Storybook Decorators to Style Components

Let's dive into the addons that come with the default Storybook template.

The 9 Best Storybook Addons to Build Better Story Workflows

Let's customize Storybook theme to match our brand!

How to Customize the Storybook React Theme for Your Brand

We have finished the first module! Let's discuss what we learned.

Wrapping up

Storybook - How it works

Now that you've learned the basics, it's time to start working on MealDrop, the main project of this course.

Section overview

We will be looking at the template project that we will use in this course.

Accessing the project

Breaking down our use-case

How to Write an Atomic Component in Storybook

Adding styled components support in Storybook.

How to Add Styled Component Themes to Storybook

Making decorators smarter with the use of globals and parameters to allow for an interactive theme switching experience.

Set Storybook Themes With Decorator Global Values and Parameters

How to Connect Storybook to Figma

How to Compose Components in Storybook

Finalizing the feature and integrating it into the app.

How to Integrate Storybook Components Into a React App

We have finished the second module! Let's discuss what we learned.

Starting the main project

It is time to learn how to deal with components that do fetch requests.

Using a container pattern to deal with complex components.

Fetch Data for Storybook Components With Container Pattern

Using conditional logic to deal with fetch requests.

Add Conditional Logic to Storybook Compontent Data Fetching

How to Mock Storybook Data Fetching Requests With MSW

Conclusion on data fetching strategies in Storybook.

Dealing with fetch requests

Let's learn how to work with page components on Storybook.

Let's add the page templates to Storybook.

Adding PageTemplate and Redux support to Storybook

Let's analyze the HomePage component and add it to Storybook.

How to add Complex Components to Storybook

Let's analyze the restaurant detail page component and add it to Storybook, including deeplinking and React portals support.

How to Add Deeplinking and React Portals to Storybook

How to Mock Storybook App Loading Scenarios With MSW

Adding Pages to Storybook

It is time to learn testing strategies in Storybook.

Let's add the official Storybook ESLint plugin

How to Install the Storybook ESLint plugin

Let's write some interaction tests directly in Storybook!

How to Use React Testing Library and Interactions in Storybook

Let's use the Storybook test runner to automate our tests!

How to Automate Storybook Testing With Test Runner

How to Run Accessibility Testing in Storybook With Addon-a11y

We have finished the fifth module! Let's discuss what we learned.

Storybook and testing

Using Chromatic for automatic Storybook deployment.

Deploy Storybook on Chromatic for Integrated Development

Using Chromatic and Storybook for visual regression testing.

Visual Regression Testing with Storybook and Chromatic

We have finished the sixth module! Let's discuss what we learned.

Deploying our Storybook

Conclusion and extra resources

Final thoughts

Storybook is an open-source tool that helps you develop UI components in isolation. It runs in your codebase, but separately from your application. It's like a sandbox, allowing you to not get distracted by incomplete APIs, flaky data, and other external dependencies. It integrates with frameworks like React, Vue, Svelte, Angular, and many others!

With Storybook, you can ease the development of a design system and share a common language with designers. QA's can get an overview and test functionalities in isolation. Stakeholders can use it for demo purposes. Overall, Storybook helps connect all of these people, greatly improving collaboration!

In this course, we will unleash the full potential of Storybook for React apps. We start from the basics of Storybook and later switch to a real world application, learning how to develop features directly in Storybook, saving lots of development time and at the same time, creating a living documentation of components and features.

You will learn how to break down features into atomic and composite components using [Component Driven Development](https://www.componentdriven.org/)

![Showing a component breakdown process](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_02/lesson_02.03/public/assets/component-breakdown.png)

You will see the power of addons, and how they help improve the development experience and the end quality of components. We will connect design tools, test accessibility, and much more.

![Figma connected to Storybook](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_02/lesson_02.06/public/assets/figspec-view.png)

You will also learn how to mock fetch requests, add Redux, theming and routing support to Storybook, and add full pages to it. You're going to even add entire pages to Storybook, allowing you to simulate all use cases you want in isolation for easy access!

![Full page in Storybook](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_04/lesson_04.04/public/assets/modal-working.gif)

On top of that, you'll be using the latest features of Storybook such as interactions, combining the power of Storybook wrappers for Testing library and Jest that run in the browser to write stories with automated interactions!

![Storybook test runner](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_05/lesson_05.04/public/assets/click-to-debug.gif)

Finally, you'll be setting up Chromatic, a cloud based tool that improves your Storybook experience by bringing you Storybook hosting and visual regression tests, in a way that will help you catch regressions but also improve the collaboration between you and your colleagues while making pull requests.

![Chromatic dashboard](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_06/lesson_06.02/public/assets/first-build.gif)

By the end of this course, you will be able to use Storybook to develop and document components, features, and pages in your work.
You'll also learn how Storybook helps you collaborate with your colleagues, both technical and non-technical (like designers and stakeholders)!

This is a course which will show you how to unleash the full potential of Storybook in the context of React applications.

Storybook for React Apps

Unleash the full potential of Storybook, adding features and pages

Tools to improve designer-developer collaboration

, we learned testing strategies that are incredibly useful for a range of scenarios. However, there is one thing that most of them lack: "eyes". Not literally, of course! Sometimes, you make small CSS changes that might not be picked up in tests and might affect the style/structure of multiple elements, which could be an unintended bug! This brings us to 

In an attempt to prevent visual bugs, visual regression testing brings an approach to give confidence when making code changes by comparing screenshots of components. It works by taking an initial set of screenshots (called snapshots) and calling them 

. Once changes are made, new snapshots are taken based on these changes, and then the 

 are compared by image processing tools. As a result, if there are visual changes, they are flagged as 

. Here's an example of regression from a button that changed its 

Of course, the visual change might be intentional, but more often than not, you might see non-intentional changes happening in your project. Usually, these changes are only noticed in production, which is 

The challenges of setting up visual regression testing

 lesson we setup automated tests for our stories. We also learned that there's a custom hook that would allow us to set up visual regression testing! But should we do that? There are quite a few infrastructural challenges when it comes to setting these up:

Thankfully, Chromatic offers visual regression testing as a service and they handle all of those things for us, so let's just use it instead!

Identifying our first regression with Chromatic

, let's see Chromatic in action by forcing some visual changes. Go to 

// src/components/Badge/Badge.tsx

// ... rest of the code

export const Badge = ({ text, className }: BadgeProps) => (
  <Container className={className}>
    <Body type="span" size="XS"> {/* <----- change this from S to XS */}
      {text}
    </Body>
  </Container>
)

Now let's create a new branch for this change:

git add .
git commit -m "change font size in badge to xs"
git push

Once created, you will see that the Chromatic GitHub Action will run and start deploying the Storybook for this PR:

After the action runs (it might take a few minutes), you will see that the checks changed in GitHub, and you now have links to the 

 which will open "Build 2", a new Chromatic build for our latest changes. In there we see all of the changes that were caught! You notice how a simple change in a basic component as the 

 actually ended up affecting many other components!

---
title: Visual Regression Testing with Storybook and Chromatic
slug: visual-regression-in-chromatic
description: Using Chromatic and Storybook for visual regression testing.
privateVideoUrl: https://fullstack.wistia.com/medias/xqa8nfxja0
isPublicLesson: false
---

In the [Testing module](./testing-introduction), we learned testing strategies that are incredibly useful for a range of scenarios. However, there is one thing that most of them lack: "eyes". Not literally, of course! Sometimes, you make small CSS changes that might not be picked up in tests and might affect the style/structure of multiple elements, which could be an unintended bug! This brings us to **visual regression testing**.

## What's visual regression testing?

In an attempt to prevent visual bugs, visual regression testing brings an approach to give confidence when making code changes by comparing screenshots of components. It works by taking an initial set of screenshots (called snapshots) and calling them **baseline**. Once changes are made, new snapshots are taken based on these changes, and then the _baseline_ and the _new changes_ are compared by image processing tools. As a result, if there are visual changes, they are flagged as **visual regression**. Here's an example of regression from a button that changed its `border-radius` and affected a page that used it:

![](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_06/lesson_06.03/public/assets/visual-diff-example.png)

Of course, the visual change might be intentional, but more often than not, you might see non-intentional changes happening in your project. Usually, these changes are only noticed in production, which is **too late**. 

## The challenges of setting up visual regression testing

In the [Storybook test runner](./storybook-test-runner) lesson we setup automated tests for our stories. We also learned that there's a custom hook that would allow us to set up visual regression testing! But should we do that? There are quite a few infrastructural challenges when it comes to setting these up:

-   We need to store the snapshots in the repo. That can become cumbersome
-   Components with dynamic content and animations are difficult to handle
-   Components that do network request are tricky to handle
-   We'd need to make sure every test runs against the same browser and version regardless of environment

Thankfully, Chromatic offers visual regression testing as a service and they handle all of those things for us, so let's just use it instead!

## Identifying our first regression with Chromatic

Following up with the [previous lesson](./setting-up-chromatic), let's see Chromatic in action by forcing some visual changes. Go to `components/Badge.tsx` and change the `size` property of the component from **S** to **XS**:

```tsx
// src/components/Badge/Badge.tsx

// ... rest of the code

export const Badge = ({ text, className }: BadgeProps) => (
  <Container className={className}>
    <Body type="span" size="XS"> {/* <----- change this from S to XS */}
      {text}
    </Body>
  </Container>
)
```

Now let's create a new branch for this change:

```sh
git checkout -b chromatic-test
```

And commit and push the changes:

```sh
git add .
git commit -m "change font size in badge to xs"
git push
```

Now create a pull request from `chromatic-test` to `main`:

![](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_06/lesson_06.03/public/assets/create-pr.png)

Once created, you will see that the Chromatic GitHub Action will run and start deploying the Storybook for this PR:

![](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_06/lesson_06.03/public/assets/chromatic-push-before.png)

After the action runs (it might take a few minutes), you will see that the checks changed in GitHub, and you now have links to the **published Storybook**, the **UI tests** and the **UI review**:

![](https://d2uusema5elisf.cloudfront.net/courses/storybook-for-react-apps/module_06/lesson_06.03/public/assets/chromatic-push-results-ui-tests.png)