Using Headless Browsers for Efficient Testing with Selenium and JavaScript

Selenium Testing

Selenium ranks among the top automation testing tools, facilitating the verification of website functionality, navigation flow, page titles, and extraction of large data sets through web scraping. Additionally, Selenium offers a remarkable feature known as Headless Browser testing, where Selenium tests are executed on headless browsers. A headless browser operates similarly to a conventional browser but lacks a graphical user interface.

However, QA professionals often need help automating real browsers using Selenium, primarily due to slow page rendering and screen consumption. You can circumvent the time-consuming CSS loading process by employing headless browser Selenium, which operates faster than conventional browsers. This proves especially beneficial in expediting the execution of complex test cases involving multiple steps, ultimately saving valuable time.

What is Headless Browser Testing?

Headless Browser Testing typically refers to the simulation of a browser without a graphical user interface (UI). In essence, it involves browser automation conducted without displaying the browser’s UI.

Headless mode enables the operation of a complete browser version while allowing it to be controlled programmatically. These operations are carried out either through a command-line interface or via network communication. Consequently, they can be utilized on servers lacking graphics or display capabilities, enabling the execution of Selenium tests.

By eliminating the rendering of web pages on the screen and executing tests without UI interaction, headless browser automation offers faster execution compared to traditional browser automation methods.

Why is Headless Execution Significant?

Conducting web automation testing on an actual browser often consumes a significant amount of time, primarily due to the loading of CSS, JavaScript, and rendering of HTML pages. Headless testing emerges as the preferred choice for those prioritizing performance.

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In the Software Development Lifecycle (SDLC), testing typically follows requirement analysis, design, and development phases. Headless browser testing aligns with a shift-left design approach, meaning it moves testing earlier in the SDLC workflow.

By implementing headless testing at an early stage, critical issues can be identified and addressed promptly by the development team, accelerating issue resolution.

A headless browser operates similarly to a real browser in accessing web pages, yet lacks the visual interface for interacting with these pages.

What is JavaScript?

JavaScript stands as a versatile and robust programming language widely employed for crafting interactive and dynamic websites. A JavaScript framework, in turn, refers to a pre-built library containing a suite of functions and tools designed for constructing either front-end or full-stack web applications. These frameworks serve the fundamental purpose of simplifying the development and management of complex web applications by furnishing a foundation for organizing and building code while handling routine tasks.

Selenium with JavaScript

Selenium WebDriver 4 has significantly enhanced its support for contemporary web standards and technologies like HTML5, CSS3, and JavaScript. This advancement facilitates developers in scripting to automate tests more seamlessly and effectively for web applications utilizing these technologies. Given the proliferation of web technologies such as Single Page Applications (SPAs) and web components, Selenium WebDriver 4’s upgraded support is a pivotal feature ensuring compatibility with these modern applications.

Another notable aspect of Selenium WebDriver 4 is its revamped architecture, ability to accommodate parallel testing, and cross-platform execution. This implies that multiple test cases can concurrently run across diverse platforms, fostering swifter and more efficient testing. This capability holds immense value for large organizations, promising significant time and resource savings.

Parallel testing enables the distributed execution of test cases, allowing multiple tests to run simultaneously. This functionality helps curtail the overall test execution duration and delivers prompt feedback. 

Selenium integration with LambdaTest further facilitates comprehensive testing. LambdaTest is an AI-powered test orchestration and execution, facilitating developers and QA professionals in conducting browser compatibility testing for their websites and mobile applications. This platform offers a scalable cloud infrastructure, enabling instant testing across various real mobile devices and browsers, including Chrome, Safari, IE, Edge, Firefox, and others.

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With LambdaTest, users can access a secure, scalable, and reliable cloud-based Selenium grid for executing automation tests. Additionally, users can conduct cross-browser testing of publicly and locally hosted websites and web applications directly in the cloud environment.

Advantages of Conducting Selenium Tests in Headless Mode

Below are the primary advantages of Selenium Headless Testing:

  • Enhanced Speed: 

Headless browser testing operates at a higher speed compared to real browsers, requiring fewer system resources for execution.

  • Improved Test Execution Performance:

Tests executed in headless mode typically run approximately twice as fast as those conducted in real browser environments.

  • Ideal for Web Scraping:

Headless testing is particularly well-suited for web scraping tasks where large amounts of data need to be extracted from web pages, such as sports or stock data retrieval. With no need to launch a real browser to verify UI elements, the focus remains solely on data extraction.

  • Efficient Resource Utilization: 

Headless testing allows the simulation of multiple browsers on a single system without incurring additional resource overhead.

  • Support for Parallel Testing:

Headless browsers offer a viable option for parallel testing scenarios where memory and resource usage are significant concerns, providing a more efficient testing environment compared to UI-based browsers.

Limitations of Headless Testing with Selenium

While Selenium’s headless browser testing offers numerous advantages, it also presents several limitations that warrant consideration. Some of these limitations include:

  • Limited support for GUI-related testing:

Since headless browser Selenium lacks support for GUI testing, certain tests, such as those assessing visual regression or requiring user interaction, cannot be conducted in headless mode.

  • Difficulty in debugging:
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Without a graphical interface to display content or errors, debugging issues inheadless mode can be more challenging compared to conventional browser mode. Developers may need to rely on logging and other debugging tools to identify problems.

  • Limited browser compatibility:

Although most major browsers offer headless mode, some older or less common browsers may not support it. This limitation can restrict the testing scope, particularly for web applications requiring testing across multiple browsers.

  • Inconsistent rendering:

In certain scenarios, the headless browser Selenium may not render web pages in the same manner as traditional browsers. This can result in inconsistencies in webpage display, element positioning, or styling.

  • Limited JavaScript support:

Some headless browsers have restricted JavaScript support, impacting the functionality of web applications that heavily rely on JavaScript. In automated tests, this may lead to false negatives or inaccurate results.

  • Difficulty in setup:

Additional setups and dependencies, such as configuring a display server or installing specific browser drivers, may be required for headless mode usage.

Performing Selenium Tests with Headless Edge

Headless Edge represents a headless browser option suitable for running Selenium tests. Here’s how to employ Headless Edge for test execution:

Step 1: Download and install the latest Microsoft Edge Driver version.

Step 2: Append the Microsoft Edge Driver path to your system’s PATH environment variable.

Step 3: Instantiate a new EdgeDriver instance in your Selenium code:

java

Copy code

EdgeOptions options = new EdgeOptions();

options.setCapability(“ms:edgeOptions”, “{\”headless\”:true}”);

WebDriver driver = new EdgeDriver(options);

Step 4: Configure the headless flag in option.setCapability() to true

Step 5: Craft your Selenium test code and execute it using the EdgeDriver

Conclusion

Choosing between headless and non-headless testing hinges on various factors including the nature of the web application under test, the testing environment, and the desired testing outcomes. If your application necessitates visualizing user interactions, then opting for headless testing may not be suitable. Conversely, if your priority lies in achieving faster execution, optimizing performance, and conserving system resources, then headless browser testing becomes a viable option. Headless Browser testing becomes particularly advantageous when prioritizing performance and time efficiency.