react-screenshot-test

by fwouts

A dead simple library to screenshot test React components

485 Stars 12 Forks Last release: Not found MIT License 366 Commits 0 Releases

Available items

No Items, yet!

The developer of this repository has not created any items for sale yet. Need a bug fixed? Help with integration? A different license? Create a request here:

Logo

CircleCI npm downloads license



Here is a screenshot test written with

react-screenshot-test
:

Code example

All you need is to install

react-screenshot-test
and configure Jest:
// 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
, just like you would with Jest snapshots.

What does it look like?

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

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
will default to running Puppeteer (i.e. Chrome) inside Docker to take screenshots of your components. This ensures that generated screenshots are consistent regardless of which platform you run your tests on.

You can override this behaviour by setting the

SCREENSHOT_MODE
environment variable to
local
, which will always use a local browser instead of Docker.

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 🙃

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.