webDriver.Quit() hangs if alert is raised in the onbeforeunload event

[zeit200]

System

• Version: 0.24.0
• Platform: Windows 10 64-bit
• Firefox: 66.0.2
• Selenium: C# 3.141.0

Testcase

using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;

namespace Test
{
    internal static class Launcher
    {
        public static void Main()
        {
            var firefoxOptions = new FirefoxOptions { BrowserExecutableLocation = @"..\firefox\firefox.exe" };
            firefoxOptions.SetPreference("dom.disable_beforeunload", false);
            var webDriver = new FirefoxDriver(@"..\geckodriver", firefoxOptions);
            webDriver.Navigate().GoToUrl("https://google.com");
            webDriver.ExecuteScript("window.top.onbeforeunload = function() { return confirm('123'); };");
            webDriver.FindElement(By.TagName("body")).Click();
            webDriver.Quit();
        }
    }
}

webDriver.Quit() never returns

[andreastt]

If you’re disabling dom.disable_beforeunload, you can’t expect the quit command to work before it relies on the prefs’ behaviour in order to be allowed to exit the application?

[zeit200]

Should it really hang indefinitely?
Setting this pref is currently the only away to verify user prompts on switching/closing pages

[whimboo]

By changing the value of the preference you enter unsupported behavior. As such we cannot help as long as w3c/webdriver#1294 hasn't been fixed.

[zeit200]

Thanks, left a comment there