Visual regression testing, which searches for unintended visual changes to a web page’s design and appearance, is a crucial part of web application testing. This approach is particularly useful when you want to ensure your online application looks professional across various releases, platforms, and browsers.
This article will use visual regression testing and Selenium, two popular automated web testing tools.
Visual Regression Testing: An Overview
User interface (UI) testing, often known as visual regression testing, confirms the aesthetic accuracy of what end users see and interact with after a website’s code has been modified. It differs from functional testing, guaranteeing that the application’s features and functions operate as intended.
Visual regression tests are intended to uncover visual “bugs” such as misaligned buttons, overlaying images or words, partially visible elements, responsive layout and rendering issues, etc., that would otherwise not be found using functional testing techniques.
For instance, the human eye can see the second web page has visual flaws. The content is illegible since the title and info texts cross over. Even worse, consumers cannot pick the “Explore Now” button because it is hidden by text. In a functional test, these flaws won’t be seen because the test can locate all the components and push the button no matter where it is. Such situations might create an extremely unpleasant user experience and potentially impair usability.
Setting Up Visual Regression Testing with Selenium
An organised strategy is required when setting up visual regression testing with Selenium to guarantee precise and effective detection of visual differences in your web applications. Here is a comprehensive step-by-step manual.
Choose an image comparison library
Image comparison is used in visual regression testing to identify visual changes. Decide on an acceptable image comparison library, such as “pixelmatch” or “Resemble.js.” Thanks to these libraries’ ability to examine screenshots pixel by pixel, you can identify even minute variations.
Set Up Baseline Screenshots
Create a collection of screenshots depicting how your web application should look. These serve as benchmark pictures for subsequent contrasts. Your program’s essential visual components and user journeys should be depicted in the baseline pictures.
Implement Test Scripts
Write Selenium test scripts to automate interactions with your web application as part of your test implementation. At key times in your application’s workflow, these scripts should do tasks like accessing websites, interacting with items, and taking screenshots.
Logic for Image Comparison
Include logic for image comparison in your test scripts. Use the chosen image comparison library to compare screenshots you’ve taken during test runs to the baseline pictures. You should be able to spot visual regressions by using the comparison logic to draw attention to any inconsistencies.
Implement a reporting system to track any concerns with visual regression. This can entail producing thorough HTML reports that specify the nature of the visual inconsistencies, screenshots of failed tests, and details on failed tests. Tracking and resolving issues effectively depends on effective reporting.
This step-by-step procedure will help you successfully set up visual regression testing using Selenium. By following this procedure, you may increase customer happiness and overall quality by ensuring your online application looks the same across all versions, browsers, and platforms.
Additionally, visual regression testing makes the testing process even more efficient by being integrated into your Continuous Integration/Continuous Deployment (CI/CD) pipeline. This enables you to identify visual regressions early in the development cycle.
Visual Regression Testing With Selenium On Cloud
You can leverage the performing visual regression testing with Selenium by executing on a cloud cloud-based platform. LambdaTest is an AI-powered test orchestration and execution platform that assists in conducting both manual and automated testing procedures across a diverse spectrum of more than 3000 actual desktop browsers, devices, and operating system configurations.
You can now ensure a flawlessly consistent digital user experience with LambdaTest’s Visual regression testing and Selenium automation framework, even at each build iteration and commit. LambdaTest supports all WebDriver and Selenium-based frameworks, as well as a multitude of programming languages.
Visual regression testing integrated with Selenium presents a sophisticated suite of AI-powered functionalities for the comparative analysis of screenshots derived from both the baseline and test outcomes. These capabilities encompass parameters such as largeImageThreshold, errorType, ignore, transparency, boundingBoxes, ignoredBoxes, and ignoreAreasColoredWith.
To start visual regression testing with Selenium on LambdaTest, you can follow the steps mentioned in the support document.
Handling Dynamic Content and Visual Variations
Setting up efficient visual regression testing with Selenium requires managing dynamic content and dealing with visual variances. Elements in web applications frequently alter dynamically due to user interactions, data changes, or other events. Here is a thorough method for handling dynamic content and graphic changes:
Use selectors that are less likely to change due to dynamic content in your test scripts to maintain stability. Do not depend on characteristics or components that change regularly. Instead, employ methods that maintain consistency even when the content changes, such as XPath, CSS selectors, or unique IDs.
Ignore dynamic content
Understand that some elements on a web page, such as timestamps or user-generated information, are anticipated to vary over time. Implement ways to disregard these dynamic or user-specific aspects during image comparison in your visual regression tests to avoid false positives. This will allow your tests to concentrate on identifying real visual regressions rather than unimportant variations.
Considerable visual thresholds should be set for your experiments. These levels consider minute variances that could arise from font rendering, anti-aliasing, or different browser rendering options. Setting appropriate thresholds guarantees that your tests only detect substantial visual changes and avoid false positives. It’s crucial to adjust these criteria based on the requirements of your application.
Automate the process of upgrading baseline screenshots whenever you purposefully alter the appearance of your web application. For instance, update the baseline screenshots to reflect the updated anticipated appearance if you change the application’s CSS styles. By doing this, you can be confident that your tests will always serve as reliable points of comparison and that valid visual changes will be noted.
Ensure your test data is uniform and under control during testing to handle visual variances brought on by various data inputs. To account for a wide range of possible visual differences, define test data that reflects a variety of scenarios and edge cases. By organizing your test data well, you can detect visual issues connected to data-driven improvements.
Regular Test Maintenance
Visual regression tests must be regularly maintained in order to remain useful. Review and update your baseline screenshots regularly to reflect your application’s current look and feel. This procedure ensures that your tests adjust to how your web application changes.
By handling dynamic content and visual variations, you may make your Selenium visual regression tests more dependable and robust. You can maintain a refined and consistent user experience across many versions and settings because they can precisely identify true visual regressions while minimizing false positives.
Continuous Integration and Visual Regression Testing
The dependability and quality of online applications are considerably improved when Continuous Integration (CI) and Visual Regression Testing are integrated. CI is a development strategy that comprises running automated tests to find problems early in the development process and continually merging code changes into a shared repository. The visual integrity of your application is maintained during iterations when CI is combined with Visual Regression Testing.
Every update to the code in a CI environment starts a sequence of automated procedures, such as building, testing, and deployment. You may automatically find visual inconsistencies brought on by coding changes by incorporating Visual Regression Testing into this pipeline. This is how it goes:
Visual regression tests are automated as part of the CI process. The CI server automatically executes these tests against the application whenever a developer submits new code or updates, frequently across various platforms and browsers.
The CI server compares recently taken screenshots of the application to baseline screenshots that have been established as representative of the desired visual appearance. It examines each individual pixel in these photos to look for differences.
The CI server flags a build failed if a test run reveals visual inconsistencies beyond the specified threshold. This immediately notifies the development team that a code change has resulted in a visual regression problem.
Visual regression testing in continuous integration (CI) gives engineers quick feedback. When an issue is found, developers can locate and fix it early in the development cycle, cutting down on the time and money needed for bug repairs.
Visual regression testing combined with continuous integration (CI) helps stop unexpected visual regressions before they reach production. The probability that consumers would see visual flaws is reduced by identifying these problems early in development.
Tracking data over time
CI solutions frequently offer build and test data over time. Thanks to historical tracking, teams can identify the exact moment and location at which a visual regression problem first appeared, simplifying tackling fundamental causes.
Automated Baseline Updates
Visual Regression Testing can assist in automating the process of updating baseline screenshots as the program purposefully evolves (such as with design updates). This minimizes false positives by incorporating actual visual changes into the baseline.
Selenium visual regression testing is a useful addition to your testing toolkit that can help you maintain a dependable and aesthetically pleasing web application. You may discover visual regressions early and provide a refined user experience by automating visual comparisons and incorporating them into your development cycle.
Striking a balance between thorough testing and effective test maintenance is crucial, though. Set explicit criteria for baseline updates, prioritize important user journeys, and fine-tune visual thresholds to prevent false positives. Visual regression testing may greatly improve the quality of your online apps and boost user satisfaction with the correct methodology and tools.