Headless Browser Testing with Selenium

As of now, you might have been running your browser automation test with Selenium, visualizing every browser event occurring from your driver script. Normally, we use the command “WebDriver driver = new ChromeDriver();” to launch an automated Chrome browser and to get a graphical user interface in our system. What if, we use the same command with just a little modification and when we run our Selenium script, our automated browser doesn’t even launch, however, our tests get fully executed?

Yes, this is possible. Let’s move forward to dive deep into this.

What Is Headless Browser?

A headless browser is one that works like other browsers, but the only difference is they aren’t visual on a desktop which means there is no graphical user interface (GUI). A headless browser is used to automate the browser without launching the browser. While the tests are running, we could not see the browser but we can see the test results coming on the console.

The Need for Headless Browser Testing

• 1) Headless browser testing is generally faster when compared to actual UI testing since it doesn’t wait for the whole page to render before performing any action.
• 2) The test can even run when there is no real browser installed in the system.
• 3) In the case of parallel testing, if we launch multiple sessions at a time, the testing can be easily done without any human intervention. Equally, the user can perform his/her other tasks simultaneously.
• 4) Few Headless Browsers like Chrome and Firefox supports screenshot functionality.
• 5) In the case of Chrome and Firefox, we can temporarily switch off the headless mode for debugging of Selenium script.

Drawbacks of Headless Browser Testing

• 1) Since the UI is not visible in Headless Browser Testing, the debugging of Selenium script becomes a little difficult.
• 2) Cosmetic bugs commonly known as GUI bugs are not identified.

Selenium Support for Headless Browsers

• HtmlUnit

  Written in Java, we can simulate various browser programs in headless mode. Selenium provides a predefined class “HtmlUnitDriver”. It supports the Htmlunit web browser which is a pure Java headless browser. It also supports HTTP and HTTPS protocols and can freely interact with web pages having submitted forms and click links.

  Note: HtmlunitDriver is only not available in Selenium version 3 or higher. To use this in your Selenium script, you need to download its jar file.

  public class Apple1 { public static void main(String args[]) throws InterruptedException { System.setProperty("webdriver.chrome.driver", "C:\\Users\\Lenovo-I7\\Desktop\\chromedriver.exe"); WebDriver driver = new HtmlUnitDriver(); driver.get("https://www.apple.com/"); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); driver.findElement(By.xpath("//*[@id=\'ac-globalnav\']/div/ul[2]/li[3]")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Heading to iPad"); driver.findElement( By.cssSelector("#chapternav > div > ul > li.chapternav-item.chapternav-item-ipad-air > a")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Checking iPad Air"); driver.findElement(By.linkText("Why iPad")).click(); System.out.println("iPad information"); driver.quit(); }

• Disadvantages of HtmlUnitDriver:

  • 1. Debugging the script is too complex.
  • 2. Doesn't support screenshot functionality

• Headless Chrome

  Before the launch of Chrome 59, the headless testing was only on third-party headless browsers such as PhantomJS(formally abandoned), HtmlUnit, etc. With an option for headless in Google Chrome, we get a chance to run our test in real browsers. To run our Selenium test in Chrome headless, Selenium provides a class called ChromeOptions. Chromeoptions is not only used to run our test in headless mode but also to set various other properties/arguments of Chrome driver.

  The headless Chrome also helps us with:

  • Full web crawling
  • Taking Screenshot
  • Gathering page information
  • Handling complex websites

  To run the test in headless mode, we just need to add a “--headless” flag using ChromeOptions.

  Example:

  public class Apple2 { public static void main(String args[]) throws InterruptedException { System.setProperty("webdriver.chrome.driver", "C:\\Users\\Lenovo-I7\\Desktop\\chromedriver.exe"); ChromeOptions chromeOptions = new ChromeOptions(); chromeOptions.addArguments("window-size=1400,800"); chromeOptions.addArguments("headless"); WebDriver driver = new ChromeDriver(chromeOptions); driver.get("https://www.apple.com/"); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); driver.findElement(By.xpath("//*[@id=\'ac-globalnav\']/div/ul[2]/li[3]")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Heading to iPad"); driver.findElement( By.cssSelector("#chapternav > div > ul > li.chapternav-item.chapternav-item-ipad-air > a")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Checking iPad Air"); driver.findElement(By.linkText("Why iPad")).click(); System.out.println("iPad information"); driver.quit(); }

• Firefox Headless Mode

  With the release of Firefox 56 version, Mozilla offered the support of headless testing. Hence, even with this, we get a chance to run our browser automation test on a real browser. Similar to Chrome, we have FirefoxOptions class to run our test in Firefox headless mode. And, we would be using the same flag “--headless” provided by FirefoxBinary which is further used to handle the properties of Firefox driver.

  public class Apple3 { public static void main(String args[]) throws InterruptedException { FirefoxBinary firefoxBinary = new FirefoxBinary(); firefoxBinary.addCommandLineOptions("--headless"); System.setProperty("webdriver.gecko.driver", "C:\\geckodriver.exe"); FirefoxOptions firefoxOptions = new FirefoxOptions(); firefoxOptions.setBinary(firefoxBinary); FirefoxDriver driver = new FirefoxDriver(firefoxOptions); driver.get("https://www.apple.com/"); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); driver.findElement(By.xpath("//*[@id=\'ac-globalnav\']/div/ul[2]/li[3]")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Heading to iPad"); driver.findElement( By.cssSelector("#chapternav > div > ul > li.chapternav-item.chapternav-item-ipad-air > a")).click(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); System.out.println("Checking iPad Air"); driver.findElement(By.linkText("Why iPad")).click(); System.out.println("iPad information"); driver.quit(); }

  Output:

  

Conclusion:

The basic objective of this article is to show how to run our Selenium Test Automation Services in a headless mode which means executing our test cases on a browser that doesn’t have a GUI. The primary reason to run our tests in headless mode is to perform maximum execution in minimum time and to perform various other tasks on the same machine without unsettling the automated browsers. So, guys give it a try, this just includes little modification in your existing test script. Good Luck, Happy Testing!!!!