When you’re developing a new product, getting every detail down to the pixel is essential. Unfortunately, adding new functionalities or updating an app can lead to unintended changes in the user interface (UI) that could damage the user experience (UX), possibly resulting in lost credibility and profitability for your business. What’s worse, some of these alterations can go undetected by functional testing, so visual regression testing is a must.
In this visual regression testing guide, we’ll explain this type of testing and why it’s so important. We’ll also show what the process entails, some benefits, challenges, best practices for its implementation, and how Ranorex can help you do it better.
What Is a Visual Regression Test?
As software evolves, even small changes in the codebase can lead to unintended visual defects. Visual regression testing checks for these by taking screenshots of the product’s webpage before and after code additions throughout the development lifecycle and comparing them to make sure nothing has changed. Some of the visual elements that a visual regression test considers are:
- Font
- Logos and brand images
- Layout and formatting
- Button location
By checking for these defects, teams can ensure that their end users enjoy a seamless user experience across all interfaces and even boost their app’s performance.
Visual Regression Testing: An Example
While visual regression testing may seem like little more than a cosmetic issue at first, its application is far more pragmatic than that. The visual discrepancies that visual regression tests can catch dampen UX and harm a product’s usability and functionality.
For example, an airliner recently experienced a glitch in its application’s development, causing the ticket purchasing button to be obstructed by the terms and conditions. This simple formatting error left potential customers unable to purchase their tickets, resulting in lost business for the company. If the company’s team had implemented effective visual regression testing techniques, it could have caught the bug before it hit production — and even converted more sales.
The Importance of Visual Regression Testing
Visual regression testing is essential for developing a quality product. Not only does it help provide a seamless user experience, but it can also enhance the usability and functionality of an application or site. A misplaced button or inaccessible feature can tarnish your brand’s appearance and even make it impossible for users to access an app’s full functionality. Some apps would fail to perform as intended without this testing.
How Visual Regression Testing Works
It can vary slightly depending on the testers’ tools, but the general method remains the same. Visual regression testing works by:
- Capturing screenshots of the interface before and after the codebase is altered
- Comparing visual changes between screenshots — either manually or with a testing tool
- Identifying discrepancies between the two
Through this process, visual regression testing can uncover significant discrepancies in your UI. Possible differences could be layout shifts, changes in color or font, or button locations, which could impact your app’s usability.
Benefits of Automated Visual Regression Testing
The benefits go beyond user experience. Visual tests can supply important insights into your app’s performance that other types of testing simply can’t offer, making them an essential part of your testing suite. Some of the main benefits are:
- Broader test coverage: Unlike functional tests, which examine data outputs given a range of inputs, visual tests let you evaluate the appearance of the actual interface. This gives you insights into your app’s real-world performance so that you can anticipate needed changes to make the most of your product.
- Faster detection: Functional tests may allow some bugs to slip through the cracks because they don’t let you inspect your product’s visual elements. Visual regression testing helps you identify glitches before they enter production, giving you faster error detection.
- Less effort: Evaluating an app’s appearance based on code changes can require careful inspection of large script blocks. Manual visual tests may be time-consuming, but they can still reveal issues faster than other regression tests — mainly if they use automation.
Another benefit, depending on your method, is increased efficiency. Some visual testing tools employ automation, reducing the workload for your team. This means that companies using automated visual testing not only build more consistent, usable products but can also perform more testing.
Best Practices
There are several best practices to remember to make the most of your visual testing tools. The most important ones are:
- Write effective tests: Your test should provide the most coverage for your app. Prioritize the highest-risk and most commonly viewed pages, like those featuring dynamic content.
- Establish baselines: Visual regression testing requires a clear baseline from which to make your comparisons, so make sure your first screenshot is correct.
- Schedule tests: Your codebase will grow quickly as you add new features and updates. Schedule your tests often enough to capture major changes, and update your baselines accordingly.
By triaging the most pressing pages, establishing clear baseline screenshots, and updating early and often, you can implement a visual regression testing system that covers more than functional tests.
Challenges
Even if you implement the key best practices, some complications could still arise. For example, manual testing can be time-consuming and reduce your testers’ efficiency. Sophisticated AI-powered solutions could also be difficult to train or install and could prove cost-prohibitive.
Thankfully, the solution to many of these challenges is simple: Choose a tool that aligns with your current environment. Regression testing providers should support you with implementation, and once they do, the burden of tedious manual testing will vanish.
Testing Tools and Technologies
Because choosing the right tool is important for implementation, teams must know which technologies are available. The most common technologies are:
- Manual visual testing tools let teams check for unwanted changes by physically reviewing screenshots of web pages. This can work for simpler apps but is highly time-consuming for more complex pages and prone to human error.
- Artificial intelligence (AI)- powered tools use computer vision to scan for differences down to the pixel, allowing for much greater accuracy.
- Document object model (DOM) tools, through which changes to the codebase are scanned instead of visual elements. This is useful for identifying which code alterations are responsible for interface changes but is not truly a form of visual testing since the actual interface isn’t checked for visual errors.
At Ranorex, we believe that AI-powered visual regression testing tools yield the best accuracy and offer the greatest efficiency gains if coupled with automation. This combination delivers the highest UX and usability while improving your testers’ efficiency.
Implement Visual Regression Testing With Ranorex
Whether you’re testing your product for the proper brand logos, colors, and fonts or ensuring that users can press important buttons to complete their transactions, one thing is sure: No detail is too small to be tested. Not only does it help you maintain your credibility by delivering the highest-quality app, but it also elevates UX and usability—and may even boost profitability.
Ranorex’s comprehensive suite of automated testing tools includes visual regression testing, removing the burden of manual testing from your team. Our flagship product, Ranorex Studio, employs AI-powered computer vision technology to catch meaningful visual discrepancies down to the pixel, removing human error from your testing processes. The result is a cleaner UI free from accidental visual defects, a superior end-user experience, and a streamlined workload for your testing team.
If you’d like to see how Ranorex can improve your visual regression testing processes, contact us to request a demo today.
