Screenshot testing, also known as visual regression testing, is a method of testing software that involves comparing screenshots of the user interface to a set of known good screenshots. The goal of screenshot testing is to ensure that the software's user interface appears as expected, and that any changes made to the software do not introduce visual bugs or other issues.
Screenshot testing can be used in various types of software development such as web development, mobile development, and desktop software development. It's particularly useful for web development as it allows to check that the website appearance is consistent across different browsers, screen sizes, and devices.
The process of screenshot testing typically involves the following steps:
Capture a set of screenshots of the user interface in its current state, this set is known as the "baseline" screenshots.
Make changes to the software, such as adding new features or fixing bugs.
Capture a new set of screenshots of the user interface after the changes have been made, these screenshots are called "regression" screenshots.
Compare the regression screenshots to the baseline screenshots, using an image comparison tool or a script, to identify any differences.
Report any differences that are found, and investigate the cause of any visual bugs or other issues that are identified.
Screenshot testing can be done manually, but it's often automated using a track website changes tool that can automate the process of taking screenshots and comparing them. Automation allows to run tests more frequently, and it reduces the risk of human error.
It's important to note that screenshot testing is not a substitute for other types of testing, such as functional testing and user acceptance testing, but it's a complementary method that helps to ensure that the software's user interface is working as expected.