@cznec/screenshot-compare

Website screenshot compare / collect.

This package is wraps:
https://www.npmjs.com/package/puppeteer https://www.npmjs.com/package/pixelmatch
for easy collect and compare website screenshots.

Package is under construction 🚧 but it works! 😉

Features

• collect: collect screenshots collection for late compare
• compare: compare new screenshots with collected screenshots

Install

npm install --save-dev @cznec/screenshot-compare

or

yarn add -D @cznec/screenshot-compare

Usage

Create collection file collection.js

const Screenshot = require('@cznec/screenshot-compare').Screenshot

module.exports = [
  new Screenshot()
    .name('github')
    .url("https://github.com/cznec/screenshot-compare")
    .delay(1000)
    .get(),
]

Run screenshots collection collect

npx screenshot-compare collect ./collection.js

Run screenshot collection compare

npx screenshot-compare compare ./collection.js

Run screenshot compare / collect on specific Screenshot() names

npx screenshot-compare compare ./collection.js name1 name1 ...

Advanced usage

Collection file

const Screenshot = require('@cznec/screenshot-compare').Screenshot

const viewport = {
  width: 1920,
  height: 1080,
  deviceScaleFactor: 1,
}

module.exports = [
  new Screenshot()
    .name('github')
    .url("https://github.com/cznec/screenshot-compare")
    .viewport(viewport)
    .delay(500)
    .saveTo('./screenshots')
    .pageLog(true)
    .get(),

  new Screenshot()
    .name('github_2')
    .before(async (page, screenshot, collector) => {
      console.log(screenshot)
      await page.setViewport(viewport)
      await page.goto("https://github.com/cznec/screenshot-compare")
      await collector.delay(1000)
    })
    .saveTo('./screenshots')
    .get(),
]

API

• Screenshot() methods:

  • url( String ) - final url for take screenshot
  • name( String ) - collection unique! screenshot name
  • saveTo( String ) - relative path from collection file to store screenshots
  • pageLog( Boolean ) - print console log of page
  • delay( Number ) - delay after url redirect and before take screenshot
  • viewport( Object ) - { width: Number, height: Number, deviceScaleFactor: Number } docs
  • before( async Function(page, screenshot, collector) )
    • page: puppeteer Page class - docs
    • screenshot: current screenshot Object ( Screenshot.get() )
    • collector: Collector class reference ( for exaple useful for Collector.delay( Number ) )

Collect command

Capture PNG screenshot and save them with name defined in collection file.
Also create screenshot definition stamp. This stamp is compared in compare command.

Compare command

Compare captured screenshots and save ..._test.png file and ..._diff.png file.
Print pixel and percentage diff.
Also check screenshot definition stamp and alert if is not equal.

More later? 🙃