Gemini is an open-source utility for automating visual regression testing of web pages. Gemini takes a screenshot of elements on a page and compares it with baseline images of these elements. If the images don't match, the differences are shown in a report. Tests are written in JavaScript and run in real browsers using the Selenium WebDriver protocol. You can work with Gemini from the command line or in the Gemini GUI. Gemini is developed at Yandex, where it is used for regression testing of block libraries and service interfaces.

Features:

• Runs parallel testing in different browsers.
• Tests various states of page elements.
• Ignores specified sections of the page during comparisons.
• Uses the box-shadow and outline properties when calculating an element's position and size.
• Restarts tests that might have failed due to external issues.
• Provides CSS test coverage statistics.