如何在 C# 中实现 WebDriverEventListener？

Question

How to implement WebDriverEventListener in C#?

I have no problem doing it in java importing:

import org.openqa.selenium.support.events.AbstractWebDriverEventListener;

However, WebDriverEventListener is not seen in C# and I cannot implement it.

Answer 1

Event listening in the C# is accomplished by using the standard event mechanism exposed by the language. You create a method with the correct signature for the event, and attach it to the event. An example method would look like this:

void MyElementClickedHandler(object sender, WebElementEventArgs e)
{
    Console.WriteLine("Clicked");
}

Attaching the event would look something like this:

// Assumes driver is a properly created
// IWebDriver instance. 
IWebDriver eventDriver = new EventFiringWebDriver(driver);
eventDriver.ElementClicked += new EventHandler<WebElementEventArgs>(MyElementClickedHandler);

Inside the event handler method, the EventArgs parameter allows you to examine attributes associated with the event. In the case of an element event, the EventArgs will have a reference to the IWebElement the event fired on. To disconnect the event handler, you use the standard C# -= operator.

Answer 2

You have to add Selenium.support.dll to your project.

Define and instantiate, event firing driver as below:

IWebDriver driver = new FirefoxDriver();

EventFiringWebDriver firingDriver = new EventFiringWebDriver(driver);
firingDriver.ElementClicked += new EventHandler<WebElementEventArgs>(firingDriver_ElementClicked);

For event to fire:

firingDriver.findElement(By.xpath("...").click();

Event is defined as:

private void firingDriver_ElementClicked(object sender, WebDriverExceptionEventArgs e) {
    // do action required to handle what happens after clicking button you have mentioned.
}

EventFiringDriver selenium source code is here and its corresponding tests are here , for your reference.

Answer 3

This link gives a nice explanation of event handling for selenium:

The events mechanism in WebDriver is composed of two major objects:

EventFiringWebDriver - A wrapper of the normal WebDriver API but adds the support of event triggering.
WebDriverEventListener - An interface with pre-defined events that EventFiringWebDriver instance will trigger.

Implementation of Event handling in Selenium as Class Diagram:

Step 1: Create a class implementing WebDriverEventListener.

public class DefaultWebDriverEventListener implements WebDriverEventListener {

    public void beforeNavigateTo(String url, WebDriver driver) {
        System.out.println("Driver will navigate to:" + url);
    }

   ...
}

Step 2: Initalize event-firing driver using the webdriver instance you have created

//initalize FireFox webdriver instance
WebDriver driver = new FirefoxDriver();
//initalize event-firing driver using Firefox webdriver instance.
EventFiringWebDriver eventDriver = new EventFiringWebDriver(driver); 

Step 3: Register the listener

//register event listener to even-firing webdriver instance
eventDriver.register(listener);

Now all the defined events in your implemented class will be executed when the selenium is executing. For instance, taking screenshot on exception etc.

Step 4: You can also unregister the listener if you want to stop firing events when selenium

eventDriver.unregister(listener);

Answer 4

Ensuring that webdriver intiated properly:

class WebDriverActionListener : EventFiringWebDriver
    {
 private IWebDriver _driver;

        public WebDriverActionListener(IWebDriver _driver): base(_driver)
        {
            this._driver = _driver;
            _driver.Manage().Timeouts().SetPageLoadTimeout(TimeSpan.FromSeconds(60));
        }

        protected override void OnElementClicking(WebElementEventArgs e)
        {
            _driver.Sync();
            string type = getTypeofElement(e.Element.TagName);
            base.OnElementClicking(e);
            Reporter.Logtofile("Clicked on element:" +e.Element.Text + " of type:" + type,Status.Info);
            _driver.Sync();
        }
}

Answer 5

yet another simpler solution for site navigation.

1. Create & Register EventFiring driver

var driver = new ChromeDriver();
EventFiringWebDriver firingDriver = new EventFiringWebDriver(driver);
firingDriver.Navigating += FiringDriver_Navigating;
firingDriver.Navigated += FiringDriver_Navigated;
firingDriver.Navigate().GoToUrl(@"https://www.selenium.dev/");

2. Declare the Event

 private static void FiringDriver_Navigating(object sender, WebDriverNavigationEventArgs e)
{
    Console.WriteLine("NAVIGATING  - " + e.Url);
}

private static void FiringDriver_Navigated(object sender, WebDriverNavigationEventArgs e)
{
    Console.WriteLine("SITE LOADED - " + e.Url);
}