Here is a screenshot test written with

react-screenshot-test

All you need is to install

react-screenshot-test

// jest.screenshot.config.js

module.exports = {
  testEnvironment: "node",
  globalSetup: "react-screenshot-test/global-setup",
  globalTeardown: "react-screenshot-test/global-teardown",
  testMatch: ["*/?(.)+(screenshot).[jt]s?(x)"],
  transform: {
    "^.+\.[t|j]sx?$": "babel-jest", // or ts-jest
    "^.+\.module\.css$": "react-screenshot-test/css-modules-transform",
    "^.+\.css$": "react-screenshot-test/css-transform",
    "^.+\.scss$": "react-screenshot-test/sass-transform",
    "^.+\.(jpg|jpeg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm|wav|mp3|m4a|aac|oga)$":
      "react-screenshot-test/asset-transform"
  },
  transformIgnorePatterns: ["node_modules/.+\.js"]
};

You can then generate screenshots with

jest -c jest.screenshot.config.js -u

What does it look like?

Here's a real example of a pull request where a component was changed:

How does it work?

Under the hood, we start a local server which renders components server-side. Each component is given its own dedicated page (e.g. /render/my-component). Then we use Puppeteer to take a screenshot of that page.

Curious to learn more? Check out the internal documentation!

Cross-platform consistency

If you work on a team where developers use a different OS (e.g. Mac OS and Linux), or if you develop on Mac OS but use Linux for continuous integration, you would quickly run into issues where screenshots are inconsistent across platforms. This is, for better or worse, expected behaviour.

In order to work around this issue,

react-screenshot-test

You can override this behaviour by setting the

SCREENSHOT_MODE

local

CSS support

CSS-in-JS libraries such as Emotion and Styled Components are supported.

| CSS technique | Supported | | ------------------------------------------------------ | --------- | |

                                     | ✅        |
| CSS stylesheets 
import "./style.css"
             | ✅        |
| Sass stylesheets
import "./style.scss"
            | ✅        |
| CSS Modules
import css from "./style.css"
         | ✅        |
| Emotion                          | ✅        |
| Styled Components | ✅        |

Usage with create-react-app

If you'd like to set up 
react-screenshot-test
 with a 
create-react-app
, here is everything you need.

Storing image snapshots

We recommend using Git LFS to store image
snapshots. This will help prevent your Git repository from becoming bloated over time.

If you're unfamiliar with Git LFS, you can learn about it with this short video (2 min) and/or going through the official tutorial.

To set up Git LFS, install the Git extension and add the following to 
.gitattributes
 in your repository (source):
**/__screenshots__/*.* binary
**/__screenshots__/*.* filter=lfs diff=lfs merge=lfs -text

You may also need to set up Git LFS for continuous integration. See our config for an example with CircleCI.

Usage with Percy

If you prefer to keep image snapshots out of your repository, you can use a third-party service such as Percy:


Install 
@percy/puppeteer

Ensure that 
PERCY_TOKEN
 is set in your enviroment
Set up a script to invoke Jest through Percy:

{
  "screenshot-test-percy": "SCREENSHOT_MODE=percy percy exec -- jest -c jest.screenshot.config.js"
}

TypeScript support

This library is written in TypeScript. All declarations are included.

Browser support

At the moment, screenshots are only generated with Chrome. However, the design can be extended to any headless browser. File an issue if you'd like to help make this happen.

Comparison

| Tool                                                                         | Visual | Open Source | Price for 100,000 snapshots/month | Jest integration | Review process                                                         |
| ---------------------------------------------------------------------------- | ------ | ----------- | --------------------------------- | ---------------- | ---------------------------------------------------------------------- |
| react-screenshot-test | ✅     | ✅          | Free                              | ✅               | Pull request                                                           |
| Jest snapshots                 | ❌     | ✅          | Free                              | ✅               | Pull request                                                           |
| Percy                                                    | ✅     | ❌          | \$469 | ❌               | Separate UI                                                            |  |
| storycap                              | ✅     | ✅          | Free                              | ❌               | Implicit approval with reg-suit |

Reporting issues

If something doesn't work, or if the documentation is unclear, please do not hesitate to raise an issue!

If it doesn't work for you, it probably doesn't work for others either 🙃