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Puppeteer

Integrating Percy with your Puppeteer scripts

Covered in this doc

Integrating Percy with your Puppeteer tests
Installing and importing percySnapshot()
Calling and configuring percySnapshot(page, <snapshotName>, <options>)

percy-puppeteer on GitHub

Package Status CircleCI This project is using Percy.io for visual regression testing.

Setup


If you're not ready to integrate Percy, check out our 2-minute Puppeteer testing tutorial and example app with Percy for Puppeteer already added.

These docs apply to version 1.0.0 or later. Previous versions of @percy/puppeteerare incompatible with what is described in this document.

Install @percy/puppeteer using npm:

npm install --save-dev @percy/puppeteer

Or using yarn:

yarn add --dev @percy/puppeteer

In order to start creating snapshots from your Puppeteer scripts or tests, you'll need to import the percySnapshot() function from the @percy/puppeteer package. You will need to do this in each file from which you want to take snapshots:

const { percySnapshot } = require('@percy/puppeteer')

You will then use percySnapshot(...) to generate a snapshot:

describe('Integration test with visual testing', function() {
  it('Loads the homepage', async function() {
    const browser = await puppeteer.launch()
    const page = await browser.newPage() 
    await page.goto(TEST_URL)
    await percySnapshot(page, this.test.fullTitle())
  })
})

Finally, wrap your script or test runner command in the percy exec command. This will start a Percy agent to receive snapshots from your tests and upload them to your Percy dashboard.

Before you can successfully run Percy, the PERCY_TOKEN environment variable must be set:

# Windows
$ set PERCY_TOKEN=<your token here>

# Unix 
$ export PERCY_TOKEN=<your token here>

For example, if you are using Mocha for your tests, your new test command becomes:

percy exec -- mocha

Note the double dash, --, between percy exec and your test run command.

That's it! Now, whenever your tests run with the percy command, a snapshot of the app in that state will be uploaded to Percy for visual regression testing!

For an example showing how to add Percy snapshots to an existing Puppeteer test suite, see https://github.com/percy/example-percy-puppeteer/pull/4.

Configuration


percySnapshot(page, snapshotName)
percySnapshot(page, snapshotName, options)

page is the Puppeteer Page object that you want to snapshot. Required.

snapshotName is a required string that will be used as the snapshot name. It can be any string that makes sense to you to identify the page state. It should be unique and remain the same across builds. For more details on generating snapshot names, see Autogenerated snapshot names.

options is an optional hash that can include:

  • widths: An array of integers representing the browser widths at which you want to take snapshots.

  • minHeight: An integer specifying the minimum height of the resulting snapshot, in pixels. Defaults to 1024px.

  • percyCSS: A string containing Percy specific CSS that will be applied to this snapshot.

  • requestHeaders: An object containing HTTP headers to be sent for each request made during asset discovery for this snapshot.

For example:

percySnapshot(page, 'Homepage test');
percySnapshot(page, 'Homepage responsive test', { widths: [768, 992, 1200] });

Global configuration

You can also configure Percy to use the same options over all snapshots. To see supported configuration including widths read our Configuration doc.


What's next

Once you've set up Percy for Puppeteer, the next step is to add Percy to your CI service. That way, every time CI runs, Percy will automatically kick off visual tests as well.

CI integration overview

Puppeteer


Integrating Percy with your Puppeteer scripts

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