Complete Guide to Visual Testing with Cypress

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VRT, often referred to as automated UI testing or visual regression testing, assesses software purely based on its visual aspects, involving the comparison of screenshots against approved reference images. Cypress is an emerging test automation framework that accelerates the delivery of high-quality products.

Cypress adopts a contemporary architectural approach and comes equipped with integrated screenshot functionality and video recording capabilities, making it a top choice for visual regression testing in Cypress.

What is Visual Testing?

Visual testing, a technique used in software testing, evaluates the visual appearance and functionality of a software application’s user interface (UI) or graphical user interface (GUI).

Visual Testing focuses on determining which parts of your UI are critical to test (Visual Coverage). Visual or HTML canvas testing is similar to functional testing in that it’s designed to be an automated process that runs alongside code reviews. However, unlike functional testing, the results of HTML canvas testing cannot be categorized as Passed or Failed.

Why is Visual Testing Important?

Visual testing plays a crucial role in ensuring that the user interface (UI) of a developed product presents itself as intended to users. It offers several valuable advantages, such as:

• Spotting flaws or irregularities in the UI design
• Detecting discrepancies in the UI that deviate from established baseline snapshots
• Crafting specialized visual test cases that encompass critical functional aspects.
• Identifying visual glitches across various web browsers

In addition, visual testing serves as an efficient and effective approach to assessing software applications. It empowers testers to pinpoint visual imperfections and inconsistencies that could potentially impact the user experience and the overall usability of the application.

Visual Testing Approaches

Various approaches are employed in visual regression testing, including:

• Developing Dedicated Visual Tests: This method involves creating assertion and validation tests from the ground up using a scripting language.

• Integrating Visual Tests with Functional Tests: Given the prioritization of functional tests during development, this approach includes visual checks that validate UI pages using existing functional test code.

• Leveraging Existing Testing Frameworks for Implicit Visual Testing: By utilizing pre-existing testing frameworks, this approach allows for general visual regression testing with minimal additional code.

The typical visual regression process encompasses comparisons, which can involve pixel-to-pixel image comparison, DOM-based comparison, or AI-driven visual comparison of UI elements.

The Role of Artificial Intelligence (AI) in Automated Visual Regression Testing

Integrating AI into automated visual regression testing addresses the issue of false positives, thereby enhancing the efficiency and accuracy of the testing process. False positives occur when testers report visual defects that do not actually exist, resulting in wasted time and resources as these erroneous results are sifted through and resolved.

Conventional methods of visual regression testing involve comparing a reference or baseline image of the desired UI with the current UI, flagging any discrepancies as visual regressions requiring attention. However, these methods possess inherent limitations that contribute to false positives, especially when dealing with dynamic content.

AI-driven automated visual regression testing tackles these challenges through the utilization of advanced algorithms and machine learning techniques. By training AI models on extensive datasets containing valid UI modifications, these models acquire the ability to intelligently differentiate between intentional changes and authentic visual regressions.

By harnessing AI in automated visual regression testing, development teams can streamline their processes, optimize the allocation of resources, and enhance the efficiency of bug-fixing procedures. Ultimately, this leads to the delivery of higher-quality applications and an improved user experience.

What is Cypress?

Cypress is an open-source automation testing tool that operates on the NodeJS platform. Tests in Cypress can be developed using either Javascript or Typescript. Cypress offers a variety of essential features for effectively automating modern web applications. Its distinctive attributes, such as automatic waiting, compatibility with single-page applications (SPA), and straightforward test debugging, set it apart in the competitive landscape.

Beyond just end-to-end testing, the Cypress automation tool also extends its support to API Testing, Unit Testing, and Component Testing. Additionally, organizations can leverage the proprietary Cypress Dashboard to gain insights into test analytics. Nevertheless, for many scenarios, the open-source version of Cypress proves to be sufficient for conducting tests.

Unique Characteristics of Cypress

Cypress stands out from other cross-browser compatibility testing frameworks due to its array of distinctive features:

• All-in-One Solution: Cypress provides a comprehensive package that includes built-in libraries, eliminating the need to install additional dependencies or components.

• Enhanced Response Time: Cypress enhances efficiency by sharing the same browser session with the application under test, resulting in quicker and more responsive test execution.

• Automated Waits and Assertions: Cypress simplifies test stability by offering automatic waits and assertions, reducing the reliance on explicit or implicit waits commonly seen in Selenium tests.

• Real-Time Updates: Cypress allows for immediate test modification and execution as it runs tests directly within the actual browser, enabling real-time updates without delay.

• User-Friendly Interface: Cypress offers a user-friendly test runner that can be executed as a graphical user interface (GUI) application, enhancing usability.

• Parallel Execution and Reporting: Cypress supports parallel test execution, ensuring efficient testing across multiple scenarios, and provides detailed reporting capabilities via the Cypress dashboard.

• Streamlined Debugging: Cypress simplifies the debugging process, making it easier for testers to identify and resolve issues during test development.

• Automated Screenshots and Video Recording: Cypress automatically captures full-page screenshots for every test event, aiding in issue identification, and provides video recordings of the entire test run for comprehensive analysis.

These unique features collectively make Cypress a powerful and efficient choice for cross-browser compatibility testing, offering enhanced speed, stability, and ease of use.

Cypress Visual Regression Testing

We can typically find plugins in Cypress that facilitate image comparison and follow the same process as snapshot testing. Cypress offers a robust foundation for developing plugins capable of conducting visual testing.

In general, these plugins capture an image snapshot of the entire application being tested or a specific element and subsequently compare it to a pre-established baseline image. When the images closely match (within a defined pixel tolerance), it signifies that the web application’s appearance remains consistent for the user. However, any disparities detected indicate alterations in the DOM layout, fonts, colors, or other visual attributes, necessitating further investigation.

This open-source plugin compares the current image with the baseline image within the Cypress Test Runner, flagging pixel differences above a specified threshold.

Executing Visual Validation in Cypress: A Beginner’s Step-by-Step Guide

Step 1: Installing the Cypress Visual Diff Plugin

Begin by installing the Cypress Visual Diff Plugin. This plugin is essential for performing visual validation in Cypress.

Step 2: Configuring the Diff Plugin

After installing the plugin, configure it according to your specific testing needs. This configuration ensures that the plugin functions correctly during your visual validation tests.

Step 3: Import and Add the Cypress Image Command

To utilize the visual validation capabilities of Cypress, import and incorporate the Cypress image command into your test scripts. This command is instrumental in capturing and comparing screenshots for visual validation.

Step 4: Writing the Test Case

Compose your test case, specifying the actions and interactions you want to test visually. Ensure that you incorporate the Cypress image command at relevant checkpoints in your test case to capture the visual state of your application.

Step 5: Executing Your Cypress Visual Test

Execute your Cypress visual test to initiate the test scenario. As the test runs, the Cypress Visual Diff Plugin captures screenshots as per your command, enabling visual validation.

Step 6: Viewing the Results

Once the test is completed, review the results. The plugin compares the captured screenshots against reference images and highlights any discrepancies, allowing you to assess the visual accuracy of your application.

Following these steps, you can effectively perform visual validation in Cypress, ensuring that your web applications maintain their visual integrity across different test scenarios and updates.

Utilizing the Visual Regression Plugin on the Cypress Cloud Grid

You can employ a Cloud Cypress Grid, an AI-powered test orchestration and execution platform, which offers automated testing across 40+ browsers and operating systems as well as parallel testing capabilities to expedite test execution in a scalable manner. This approach enhances the overall visual test coverage, allowing you to assess various combinations using the same test scripts. also provides visual regression testing with Selenium.

Cypress visual regression testing on the cloud, when combined with platforms, offers the advantage of achieving comprehensive visual test coverage without requiring modifications to the core logic of your test code for multiple OS and browser compatibility. This approach streamlines the testing process and enhances the reliability of your visual tests.

Conclusion

Visual Regression Testing in Cypress enables testers to employ various Cypress plugins for capturing screenshots or visual snapshots at different stages of application development. These captured images serve as reference points, depicting the expected appearance of the application at specific milestones. In subsequent test executions, new screenshots are generated, and a comparison is made against these reference images to identify any visual disparities.