Using JMeter for Headless Browser Testing

Other Questions Headless Browser
1

I attempted to set up a headless browser test in JMeter with the jp@gc - HtmlUnit Driver Config, but encountered an error that states: ‘com.gargoylesoftware.htmlunit.ScriptException: ReferenceError: “getComputedStyle” is not defined.’ After researching, it appears that the driver does not support JavaScript. Is there a solution to this issue within JMeter, or are there alternative methods for performing headless browser tests? I am utilizing a Linux server for the load testing. Additionally, I’ve created a WebDriver sampler to access the Google homepage using the following code: WDS.sampleResult.sampleStart(); WDS.browser.open(‘http://google.com’); WDS.sampleResult.sampleEnd(); I also downloaded PhantomJS, but it doesn’t generate any output in the report. Do I need to make further configurations?

2

The challenge you're facing with JMeter's HtmlUnit Driver not supporting JavaScript is a common limitation. While the HtmlUnit Driver is lightweight and easy to use, its JavaScript execution capabilities are not comprehensive, leading to issues such as the missing getComputedStyle function in your scripts.

An alternative approach involves leveraging the capabilities of Selenium WebDriver with headless browsers like Chrome or Firefox, which can execute JavaScript more reliably. However, since Selenium might not be the most effective for certain JMeter use cases due to increased overhead, consider these tailored approaches for achieving your headless browser testing:

Using Docker with Headless Browsers

To maintain a balance between performance and capability, you might want to consider using Selenium with a headless browser containerized in Docker. Here's the basic idea:

  1. Install Docker on your Linux server if you haven't already.
  2. Run a Selenium server with a headless Chrome or Firefox instance using an official Docker image. For example:
docker run -d -p 4444:4444 --shm-size=2g selenium/standalone-chrome:latest

This approach allows JMeter to execute browser-based tests more effectively by offloading the heavy-lifting to a containerized environment, thus avoiding the limitations of HtmlUnit Driver.

Implementing a Remote WebDriver

If Docker is not an option, you can configure JMeter to use a remote WebDriver:

DesiredCapabilities capabilities = DesiredCapabilities.chrome();
capabilities.setCapability("headless", true);
WDS.browser = new RemoteWebDriver(new URL("http://localhost:4444/wd/hub"), capabilities);
WDS.sampleResult.sampleStart();
WDS.browser.get('http://google.com');
WDS.sampleResult.sampleEnd();

This setup allows you to connect to a Selenium Grid or standalone instance running on your network, giving you access to a more robust JavaScript execution environment.

For further configurations, ensure all necessary WebDriver binaries (like chromedriver) are present and properly set in your PATH. Moreover, consider adjusting advanced capabilities required for your testing scenario according to the documentation of the browser you choose.

Adopting these methods enhances your testing capability, ensuring comprehensive JavaScript support while maintaining the headless nature of your tests.

3

JMeter's HtmlUnit Driver has limited JavaScript support, which often leads to errors like yours. An effective alternative is using the Selenium WebDriver Sampler with a headless browser like Chrome or Firefox. Here's how you can switch:

ChromeOptions options = new ChromeOptions();
options.addArguments("--headless");
WDS.browser = new ChromeDriver(options);
WDS.sampleResult.sampleStart();
WDS.browser.get('http://google.com');
WDS.sampleResult.sampleEnd();

Ensure relevant drivers (like chromedriver) are on your path. For PhantomJS, it's deprecated, so using Chrome or Firefox is recommended. Adjust configurations as per your server's compatibility. Hope this helps!