Wraith : A responsive Screenshot Comparison Tool

Wraith is a screenshot comparison tool, created by developers at BBC News.

Documentation • Source • Responsive News Website

What is it?

Wraith uses a headless browser to create screenshots of webpages on different environments (or at different moments in time) and then creates a diff of the two images; the affected areas are highlighted in blue.

Documentation

For instructions on how to install, set up and use Wraith and all of its features, visit the Wraith documentation.

A brief overview of how Wraith works is provided below.

Wraith modes

There are several ways in which Wraith can be used:

Comparison of 2 domains (wraith capture). There are also some specialist options within this mode:
- Spidering 2 domains for changes (wraith capture when no paths property is provided in the configuration file)
- Running several comparisons at once (wraith multi_capture)
Comparing the same domain over time (wraith history, then wraith latest)

Whichever mode you decide to run Wraith in, the process it follows is generally the same:

takes screenshots of your webpages
runs a comparison task across them
outputs a diff PNG file comparing the two images, and a data.txt file which contains the percentage of pixels that have changed
packages all of this up into a gallery.html, ready for you to view
if any screenshot's diff is above the threshold you specified in your configuration file, the task exits with a system error code (useful for CI)
the failed screenshot will also be highlighted in the gallery

Requirements

ImageMagick is required to compare the screenshots and crop images.

Wraith also requires at least one of these headless browsers:

PhantomJS
CasperJS (which can be used to target specific selectors)
SlimerJS
Chrome (Currently using Selenium WebDriver + Chromedriver for Chrome; Can target specific selectors)

Contributing

Please read how to contribute to Wraith.

License

Wraith is available to everyone under the terms of the Apache 2.0 open source license. Take a look at Wraith's LICENSE file.

Credits

Selenium-Wraith

Anyone interested in integrating selenium capability with Wraith should check out Selenium-Wraith (maintained by Mathew Hall), which was forked from BBC's Wraith on 16/04/14 and adds the following capabilities:

Selenium integration, both running locally on a desktop or on a selenium grid
Browser to browser screenshot comparison
Page component-based comparison