Selenium testing without browser.

Last Updated : 15 Oct, 2024

Selenium Testing without Browser is a method of running automated tests without launching the browser's graphical user interface (GUI). This is achieved using headless browsers, which allow tests to run faster and consume fewer resources. It is ideal for regression testing, continuous integration, and environments like Linux servers where no GUI is available. By running tests in a headless mode, you can validate back-end functionality without the need for visual rendering, making the process highly efficient.

Table of Content

What is Cross Browser Testing?

Testing which is done on Multiple Browsers is referred to as Cross Browser Testing. It can be performed on both Web and Mobile Applications, For Example, at times an application or Website might be working out well in Chrome Browser, however, if you switch to some other browser such as Firefox then it will not work properly, or this happens due to lacking Browser Compatibility Testing.

Need of Cross Browser Testing

When the Website or Application is prepared for Public use, like e-commerce, then it needs to be tested on numerous Browsers for a Smooth and Good Quality Experience.

Layout Issue : The structure of a Website or Application may vary while opening in Every Browser, For example, Buttons, Images, Fonts etc.
CSS/JavaScript Compatibility : Every browser interprets CSS and JavaScript differently. Thus, some functionalities such as animations fail.
Browser-specific bugs (plug compatibility): Certain specific libraries or plugins do not work on every website.
Page Alignment & Div Size.

Headless browser in selenium web driver

A headless browser is a browser simulation program that does not have a user interface (UI less). Headless browser programs operate like any browser but not display any user interface selenium executes its test in the background. There are several headless browsers available in the market the following are the most popular once.

Chrome
Firefox
HTML Unit driver (by default it is a Headless browser)
Phantom JS

What is Headless testing?

Executing the web application user interface test without opening a browser user interface is called headless browser testing. Headless browser acts similar to a normal web browser.

Testers have full control over the web pages loaded into the headless browser only difference is you will not see a graphical user interface.

When to use Headless browser testing?

We can use Headless browser testing once the cross browser testing is completed and want to run regression test cases in subsequent releases and with continuous integration.
You have no option other than using Headless testing when your machine does not have a graphical user interface, for instance if you want to run your tests in Unix.
It is recommended to use Headless browser when tests are executed in parallel as user interface based browser consumed lot of memory/resources.
Headless browser is very faster when you compare it with normal execution or traditional execution on the browser's user interface.

Disadvantages of Headless browser testing

Headless browsers are a bad idea. They get you some testing, but nothing like what a real user will see, and they mask lots of problem that only real browsers encounter.
Hard to debug inconsistent failures on locating elements due to page load too fast.
In Real browser as functions are performing in front of user and he can interact with it, so he can easily detect where the test goes fail and can easily the debug if anything goes wrong.
Headless browsers aren't representing real user as no user uses your application without user interface because it does not have user interface it may not report error related with images.
Managing to take screenshot is very difficult in user interface less browser.

How to set up Selenium WebDriver, with Headless testing for Chrome?

Step 1: Install Java

Download and install the latest version from the official Java website after that Verify the installation by running the following command in your terminal.

java -version

Step 2: Install Browser Drivers

Selenium requires a browser driver to control browsers. For Chrome, you need ChromeDriver, and for Firefox, you need GeckoDriver and then Download the appropriate driver from their official sites and place it in your system’s PATH.

Step 3: Install Selenium Libraries

First Add Selenium libraries to your project.

If using Maven, include the following in your pom.xml:

XML

<dependency>     <groupId>org.seleniumhq.selenium</groupId>     <artifactId>selenium-java</artifactId>     <version>4.9.0</version> </dependency>

Step 4: Configure Selenium for Headless Testing

For headless mode, you need to configure the browser to run without UI rendering.

Here’s an example for Chrome

Java

 ChromeOptions options = new ChromeOptions();      options.addArguments("--headless");  // Enables headless mode      WebDriver driver = new ChromeDriver(options);

Here's an Example for Firefox

Java

FirefoxOptions options = new FirefoxOptions();      options.addArguments("--headless");      WebDriver driver = new FirefoxDriver(options);

This configuration runs Selenium WebDriver without opening the browser window, making the tests faster and more resource-efficient.

Implementation of Selenium testing with Headless testing for Chrome

HeadlessChrome.Java

package headless;  import org.openqa.selenium.WebDriver; import org.openqa.selenium.chrome.ChromeDriver; import org.openqa.selenium.chrome.ChromeOptions;  public class HeadlessChrome {      public static void main(String[] args) {          System.setProperty("webdriver.chrome.driver", "C:/Drivers/chromedriver_win32/chromedriver.exe");          // Setting up Chrome options for headless mode         ChromeOptions options = new ChromeOptions();         // Enable headless mode by passing the argument         options.addArguments("--headless");          // Initializing WebDriver with the headless Chrome options         WebDriver driver = new ChromeDriver(options);          // Navigate to a demo website         driver.get("http://demo.nopcommerce.com/");          // Print the title of the page         System.out.println("Title of the page: " + driver.getTitle());     } }

Running Selenium Tests with HtmlUnitDriver in Headless Mode:

Why is HtmlUnit Browser Used?

Another headless browser which is mainly utilized in automation testing is the HtmlUnit browser. Such type of browsers can run without a GUI. In such cases, the visual rendering of the website is not important. Tests will run faster as well as in a more efficient manner without all the visual rendering, hence making it lightweight and requires lesser resources. That is why a browser like HtmlUnit is especially good at speeding up testing when applied in continuous integration pipelines for running automated test suites.

HeadLessHtmlUnitDriver.java

package headless;  import org.openqa.selenium.htmlunit.HtmlUnitDriver;  public class HeadLessHtmlUnitDriver {      public static void main(String[] args)     {         HtmlUnitDriver driver = new HtmlUnitDriver();          driver.get("http://demo.nopcommerce.com/");          System.out.println("Title of the page:"                            + driver.getTitle());         System.out.println("The current URL of the page:"                            + driver.getCurrentUrl());     } }

Output

Benefits of Selenium Headless Testing

Faster Execution: Headless testing is considerably much faster than the normal browser test executions since no graphical user interface needs to be loaded, thus making the tests cheaper and faster in terms of operations.
Resource Efficient: Since no graphical interface is rendered, it results in few system resources being consumed (on the CPU and memory) for the headless testing, and it thus becomes perfect to run tests on low-powered servers or cloud environments.
Continuous Integration (CI) Friendly: Headless browsers can be easily plugged into CI/CD pipelines to run headless tests even in environments without a display such as Docker containers or remote servers.
Parallel Testing: Headless testing also can be conducted in parallel by many instances wherein test execution is accelerated by a big deal more so for very large test suites.
Headless mode supports popular browsers like Chrome and Firefox, but allows to do all the cross-browser testing without GUI.
Headless testing is best for those tests that deal with the back-end functionality like submission of forms, database interactions, and API responses where visual UI validation does not play a part.
Efficient Performance of Regression Test: Headless Testing is also good for regression tests; they are more into speed and accuracy than executing, so it helps in pacy test cycles.
Ideal for Non-graphic Environments: Headless testing becomes very crucial in the environments that do not have a GUI, such as Unix/Linux servers, since it does not rely on the graphical interface to run any tests .
Automate Background Processes: Used to automate the processes of testing that do not need user interaction like API, for example, or to run the backend operations without waiting for browsers to render visuals.

Limitations of Selenium Headless Testing

Headless browsers are a bad idea. They give you some testing, but nothing at all like a real user will see, and they hide much of the problem that only real browsers encounter.
Hard to debug inconsistent failures on locating elements due to page loading too fast.
In Real browser because of functions are performing in front of the user and he can interact with it, so that he can easily find where exactly the test goes failing and can easily debug if anything goes wrong.
Headless browsers aren't representing real user as no user uses your application without user interface because it does not have the user interface it may not report error related with images.
Taking a screenshot is extremely tough in an un-user interface browser.

Conclusion

In conclusion, Selenium testing without browser is a powerful approach for speeding up tests, especially in CI/CD pipelines where resource efficiency and speed are crucial. While headless browser testing has clear advantages in terms of performance, it should be balanced with full browser testing to capture potential UI bugs and visual issues. For back-end operations, Selenium headless testing is an excellent choice, providing a fast and reliable method for automating tests in environments without a graphical interface.

Parallel Testing with Selenium

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