How To Get Started With Visual Regression Testing on Cloud?

Regression Testing

Ensuring the quality and reliability of web applications holds paramount significance within the swiftly evolving realm of software development. Preventing inadvertent visual bugs resulting from codebase updates and promptly addressing any identified issues are imperative tasks for developers. Neglecting these aspects can precipitate visual glitches within the application, thereby compromising user experience. To this end, the employment of visual regression testing emerges as a vital practice, facilitating the identification and resolution of visual disparities across diverse iterations of a web application. In this article, you will see what visual regression testing is and how this testing is useful when performed using cloud resources.

Defining Visual Regression Testing

Visual regression testing is a software testing methodology that involves the comparison and validation of the visual appearance of a web application or user interface across multiple versions or states. The primary objective of visual regression testing revolves around the detection of unintended visual alterations or inconsistencies that might arise due to modifications in code, updates in CSS, or other changes introduced during the development or maintenance phases.

Unlike conventional functional testing, which primarily focuses on verifying an application’s functionality and behavior, visual regression testing predominantly concentrates on scrutinizing the graphical elements of the user interface. Its core objective lies in ensuring the steadfastness and flawlessness of the program’s visual constituents, layout, and design throughout the entirety of the development lifecycle.

There are various benefits of performing visual regression testing on the cloud that you will see such as it is highly scalable, it is flexible, easy team collaboration and support, etc.. It is very important to detect and rectify the visual bugs in your software and website before making them live. Because they will affect the user experience in a very negative manner, because they will be a component of a user’s first impressions, it should be seamless and user-friendly.

Various Methods for Visual Regression Testing in Cloud

Basically, visual regression testing is the process of testing your software applications by making visual comparisons to enhance the user experience, specifically the features and functionality that are related to the visuals of a software application. This process includes taking screenshots of the application before and after applying any kind of change to them. Then, a comparison is made between these before and after screenshots. Here are some of the common methods to get started with visual regression testing in cloud:

Manual Visual Testing

This approach of visual regression testing is the practice of testing the software application without using any advanced AI tools and resources. In this testing, each application page is analyzed one by one, and then the testers find any potential errors or bugs. This type of visual regression testing is very important and useful in the early stage of the software testing process.

This is because it allows ad hoc testing of the user experience of specific software. This method has many advantages, but also there are some cons of this testing process, such as it takes more time to complete the visual regression testing because all the steps are done manually one by one.

Layout Comparison

This approach of visual regression testing is used to perform testing against the size and location of each component over the page of a software application. The Testing is done only by taking the parameter size and location of elements rather than the pixel or any other factor. There is also a method that follows the testing using the pixel that you will see in the following section.

Pixel-by-Pixel Comparison

This approach of the visual regression testing process is done using the screenshots of the software and comparing them by pixel. When the testing process starts, the testing team takes a screenshot of each step before the test, during the test, and after the testing. Then, they compare these screenshots based on pixel factor. If any inconsistency or error is found, the testing team communicates with the testing engineers and modifies the changes accordingly.

This testing is very effective in visual regression testing. But sometimes, it becomes hard to analyze the differences between the screenshots. Because it also captures minor visual differences, such as margin, rendering of frames, etc., that are invisible to the naked human eye.

Structural Comparison

This approach of visual regression testing is used when you want to compare the DOM structure. As we know, the DOM structure defines the HTML markdown. This change affects the overall view of the software application. If any DOM structures are mismatched, the testing process fails.

DOM-Based Comparison

This approach of visual regression testing is done when you want to perform a layout comparison. Comparing UI elements visually and evaluating their sizes and positioning comes first. In other words, the Document Object Model serves as the foundation for comparing DOM analysis results before and after state changes, with differences then being detected.

As a result, this highlights changes to the DOM code. The results of the tests could, however, be faulty. As a result, testers must go through them slowly and carefully to stop visual bugs from escaping.

Visual AI Comparison

This approach of visual regression testing is done when you want to test your software application for the user experience using AI. In this process, two visual representations are created with the help of artificial intelligence and machine learning. These two images are created just by mimicking a normal human user. The Tools provide their feedback just like a normal human being. Then, the comparison of these two images is done to find any flaws and errors in the software application.

Inserting Visual Checkpoints and Validation

You already have the requirements to verify the features and functionalities when you use them for implementing visual checkpoints in functional tests. To validate the pages, you just add visual checks in between these functional tests. Utilizing the existing code for functional tests is an excellent strategy. To validate these analyses, you have huge resources for this method of visual regression testing.

It consists of adding those validations to the existing verified code of your software application. This helps to save time for writing the code again and again. You can use the new add-ons in the existing code base that improves the testing efficiency and performance in less time.

Implementing Visual Regression Testing

Incorporating visual regression testing into your development process can significantly elevate the caliber and stability of your web application. By comparing screenshots of the application across various versions, any inadvertent visual alterations or glitches can be swiftly identified and resolved, guaranteeing a seamless user experience.

Selecting the Appropriate Testing Approach

 Visual regression testing can be executed through several methods, each offering distinct advantages and constraints. Here are three primary approaches:

  • Full-Page Screenshots: This method involves capturing screenshots of the entire website during the reference phase. Another screenshot is taken during subsequent testing, and a tool then compares it against the reference image to uncover visual disparities. While this approach is straightforward, it may result in false positives due to minor dynamic content changes.
  • Element-Level Comparisons: Rather than assessing the entire website, this method focuses on specific components like buttons or headers. While providing more precise insights into aesthetic inconsistencies, it requires a careful selection of elements.
  • DOM Snapshot Comparisons: This strategy entails taking a snapshot of a page’s DOM structure and comparing it with earlier versions. Though potentially more complex to implement, it offers a high degree of accuracy.

Choosing the Right Tool

Given below are the best testing tools to perform visual regression testing on the cloud and execute your testing process.

  • LambdaTest: LambdaTest allows the testing team to perform visual regression testing for both mobile applications and websites by providing many options such as icon size, color format, layout, etc. It is a cloud-based digital experience testing platform with the capability to conduct visual regression testing across expansive online farms of over 3000 browser and operating system combinations.

The LambdaTest platform streamlines automated visual testing through Selenium and Cypress, extending support to various programming languages including Java, Node.js, and C#. This approach guarantees the delivery of impeccably refined software applications from a visual perspective. An extra perk is the availability of parallel testing, substantially curtailing the time investment required for test execution.

Key attributes housed within LambdaTest’s Smart UI (visual regression) testing cloud comprise:

  • Elevated customization options for visual testing, encompassing parameters like largeImageThreshold, errorType, ignore, transparency, and more.
  • Harnessing the potential of Webhooks to further elevate the intelligence of your testing process.
  • Tapping into LambdaTest’s diverse array of choices, including antialiasing, alpha, and color settings, effectively minimizing the likelihood of instability in the comparison output of your compressed screenshots.

Establishing a Reliable Baseline

A robust baseline is indispensable for dependable visual regression testing. This baseline serves as the reference point for all subsequent tests. Opt for a visually stable version of the application as your initial baseline.

Managing Dynamic Content

Web applications often feature dynamic data, such as user-generated content or real-time updates. Handling dynamic elements is crucial for effective visual regression testing. Techniques like ignoring insignificant dynamic aspects or applying masking methods can enhance accuracy.

Integrating with Continuous Integration (CI)

To fully harness its advantages, integrate visual regression testing into your continuous integration (CI) workflow. This entails conducting automated visual regression tests with every code commit, enabling swift feedback on visual modifications and upholding visual coherence.

Optimal Approaches in Visual Regression Testing

  • Standardized Testing: Establishing a set of consistent testing scenarios and scripts ensures uniformity across browsers and devices during the testing process.
  • Enhanced Screenshots: Elevate screenshots by incorporating annotations to highlight problematic areas. This expedites issue comprehension and resolution for engineers.
  • Regression Test Repositories: Develop repositories of test cases encompassing common user interactions. Regularly executing these tests aids in promptly identifying potential regressions arising from code alterations.
  • Collaborative Developer Engagement: Sustain transparent communication channels with developers during collaborative efforts. Address identified disparities collaboratively to devise effective remedies.
  • Guideline Documentation: Document comprehensive testing standards, guidelines, and universally acknowledged visual norms. This documentation serves as a valuable point of reference for both testers and developers.
  • Continuous Skill Enhancement: Foster a culture of ongoing improvement among testers by keeping them informed about design trends, accessibility criteria, and browser behaviors.

While manual testing demands substantial effort, it infuses a human element that complements automated methodologies. A well-structured manual testing approach bolsters the overall quality of your cross-browser visual regression testing strategy.

Read : How To Run Your First Cross-browser Test?


Visual regression testing emerges as an essential cornerstone in the realm of web application development. This technique empowers teams to forge web applications that embody a seamless and consistent user experience, effectively mitigating inadvertent visual discrepancies. By adhering to the implementation methodologies and optimal practices delineated in this guide, developers can seamlessly integrate visual regression testing into their development workflows. This integration facilitates the creation of high-caliber web applications that captivate users through their unwavering visual excellence.