It is crucial to test the functionalities of your website or web application and their appearance to the end user before their deployment to a live environment. There are different kinds of manual and automation testing available that can help you to test your web page as per the user’s requirement.
Automated screenshot testing is one of the popular software testing types that can help you accomplish a high-end-user experience and proper visual testing.
It allows you to test your webpage using just a few lines of code and enables you to verify whether your website is being rendered correctly. As a result, developers and QAs are entirely aware of what is being released to end users. Some of the essential aspects of automated screenshot testing will make it easier to carry out your test.
This is the main aim of this beginner’s guide to automated screenshot testing article. We will cover working, advantages, tools, and ways to perform automated screenshot testing. So, without any further ado, let’s start.
What is Automated Screenshot Testing?
Automated screenshot testing is the process of taking screenshots of web pages in bulk and comparing them with the expected image of web pages based on the requirement. It is also known as visual regression testing. Instead of using simulators, screenshot testing uses real devices and browsers and guarantees that the website will seem precise as it would to a user.
The UI of a web application can be visually compared between versions or environments via automated screenshot testing. It offers immediate feedback on visual changes that are generated by changes to the system’s code. Automated screenshot testing on different browsers, desktops, operating systems, and mobile devices can be used. Since you can test your website across many browsers, you must be able to highlight the bug or issue in the web page’s images without having to write extensive problem reports. It’s easy to use and makes it less challenging to spot visual changes in the web page’s user interface as update iterations occur.
When to use Automated Screenshot Testing?
Automated screenshot testing can be performed while executing UI testing. By performing UI testing, testers can ensure that all the fields, labels, buttons, and other elements on the screen work as intended. Let us understand this with an example.
Consider a situation when you are running your application using the Microsoft Edge browser. Here you need to perform automated screenshot testing, and for this, you can take a snap and view the image side by side with Safari, Firefox, and Opera in one go.
Consider one more scenario when your data is not random, for example, the current timestamp, and you need to verify the expected outcomes on the website. In that case, you can also use the automated screenshot to compare the screenshot with the expected result instead of comparing the data field by field.
Comparing images is more complex than comparing text, So before using automated screenshot testing, you should take care of the following factors:
- It would help if you took care of the resolution used by your system during the testing.
- The rendering of the fonts and styles can sometimes be an issue because they vary from one computer to another or even from one browser to another.
Tools for Automated Screenshot Testing
You can perform automated screenshot testing in local systems and cloud-based services that can test many operating systems and web browser combinations. Various tools or platforms will allow you to perform automated screenshot testing efficiently. Let’s explore some tools you may use to verify your web page’s screenshots before releasing them to the end users.
- LambdaTest:It is an AI-powered test orchestration and execution platform that can allows you to perform automating screenshot testing that helps streamline the process of capturing bulk screenshots across diverse desktops and mobile devices running on various operating systems simultaneously. It utilizes instrumented UI test cases to evaluate how effectively your web app renders across different screen sizes and browsers.
At LambdaTest, you have the capability to capture up to 25 screenshots in a single session, each depicting various browser and OS configurations. Choose from an extensive selection of browser versions, ranging from the latest to the oldest, including Chrome, Firefox, Safari, Edge, Internet Explorer, and Opera. Additionally, you can conduct tests on different operating systems, including Windows, macOS, Android, and iOS.
- Selenium WebDriver: You can automate browser operations with Selenium WebDriver, including opening a URL, browsing web pages, interacting with UI elements, and taking screenshots. Image comparison features are not included in Selenium WebDriver itself. You can, however, integrate frameworks, tools, or libraries for screenshot comparison from other sources into your automation framework. Selenium WebDriver supports Ashot API (a third-party Yandex app) to take screenshots.
- Playwright:You can create screenshots and compare them with recent screenshots using Playwright’s automated screenshot testing. Screenshots will be attached to the HTML report and visible in the test output directory, usually called test results.
- Appium: With the flexible cross-platform testing framework Appium, developers can use the same API for a variety of platforms, including iOS, Windows, and Android. When an assert condition fails, you can use Appium screenshots to report errors or record how the app appears to end users.
- Puppeteer:The Google team is in charge of the automation testing framework known as Puppeteer. Before using visual testing, you must incorporate assertion libraries like Mocha, Jasmine, or Jest because Puppeteer, by default, doesn’t have any assertion libraries.
How to Perform Automated Screenshot Testing?
Automated Screenshot testing never asserts the application’s features, in contrast to many other UI(User Interface) testing techniques. It includes an output evaluation instead. In other words, rather than demonstrating whether the code is effective, this technology ensures that your output behaves as per the end-users requirements.
Here is a list of important steps to help you understand how to perform screenshot testing.
- Setting Up the Environment: The first step to perform the automated screenshot testing is to install all the required tools, frameworks, packages, libraries, etc. Ensure the website or webpage you wish to test is accessible and not broken.
- Choose an appropriate testing tool: You can choose your desired testing tool as per your requirements. For example, Selenium WebDriver,Cypress, Playwright, etc.
- Automated test script implementation: Next step is the implementation of automated test scripts. The scripts need to provide guidance on how to access the target page, interact with elements if necessary, and take screenshots as needed throughout the test flow.
- Define the test cases: Decide which particular test case of your web page you wish to examine. These test cases include user interactions, various UI components, particular visual components, or multiple web pages.
- Baseline Screenshot: Capture baseline screenshots of the webpage in an acceptable state. These screenshots will be used as a reference in further comparisons.
Automate the process by using the testing tool’s features or techniques to take screenshots at particular checkpoints or after particular activities.
- Comparison of images: Using the picture comparison techniques offered by the testing tool, compare the screenshots that were collected with the baseline screenshots.
- Results Analysis: Examine the test results to determine whether the variations are to be expected or whether they point to possible visual-related problems.
- Updation: Update the test cases to account for user interface changes as the web application develops. Additionally, update the baseline screenshots also to reflect the web application’s current visual condition.
- Add to the CI/CD pipeline: One can include the automatic screenshot tests in their pipeline for continuous deployment and integration process.
- Monitoring: Test execution should be monitored, and any failures should be quickly resolved. This can be done by finding the root cause of the problem by identifying actual features.
Advantages of Automated Screenshot Testing
Here are a few advantages of automated screenshot testing:
- Automated screenshot testing reduces testing time and also helps in avoiding manual-related mistakes.
- It improves tracking changes to a web page or web app.
- It is simpler to maintain because only a few lines of code are often used in screenshot testing.
- Traditional techniques for testing may ignore a program’s visual elements but automated screenshot testing enhances test coverage by ensuring that visual components are fully examined in addition to existing testing techniques.
- By comparing current screenshots with baseline snapshots, automated screenshot testing can assist in finding various regression issues and prevent them from continuing undetected.
Disadvantages of Automated Screenshot Testing
Here are a few disadvantages of automated screenshot testing:
- The absence of test-driven assistance is one of the drawbacks of screenshot testing. So, it’s not possible for the testers to manually develop screenshot test files or records.
- When the screenshot is large, and many developers are working on the same component, it may cause merge conflicts.
- The baseline screenshots of automated screenshot testing must be constantly updated to reflect the updated intended state as the web application develops and the UI changes. Hence, we can say that the maintenance of automated screenshot testing can be difficult.
To conclude, automated screenshot testing is an excellent process for ensuring your UI never changes unexpectedly. It is a good technique to evaluate the quality of a webpage or web app while showing it to actual users. It has many benefits, including expanding test coverage, ensuring that visual components are fully examined, and monitoring how changes impact results.
Since its launch, automated screenshot testing has gained popularity among developers, mainly due to the easier syntax for creating tests than the conventional method. Even though this testing approach is excellent, you must be careful when using it. Never accept any changes in your tests carelessly. Also, despite the fact that automated screenshot testing is easier to use, you should never substitute snapshot tests with unit or functional tests.