puppeteer.md

Phantom Pain

Joel Griffith - Sr. Dev @ AppNexus (Twitter: @griffith_joel)

Sample repo: joelgriffith/phantompain

Background

• worked with phantomjs to run unit test suite
• switch to headless chrome
• phantomjs dev said, "peace"
• what about site snapshots, visual regressions, functional testing, ...

Some things are hard with react

• take a screenshot of a webpage (e.g. for twitter, social media, etc)
• puppeteer (headless chrome library) makes this fast and easy
• simulate search engine requests w/o server-side rendering? yes, we can

Also good for improving functional tests

• page.evaluate - define and execute a method within the page. Useful for loading libraries, injecting XSS attempts, etc.
• works neatly with mocha, jasmine, jest, whatever--even with jest.concurrent (browser sessions are indepnedent)

And visual regressions

• use jest-image-snapshot (.expectImageSnapshot) to generate binary visual diffs

Thanks, Joel!!