AdvancedWebDriverUsageTests.cs

[TestMethod]
public void JavaScripPopUps()
{
    this.driver.Navigate().GoToUrl(
    @"http://www.w3schools.com/js/tryit.asp?filename=tryjs_confirm");
    this.driver.SwitchTo().Frame("iframeResult");
    IWebElement button = driver.FindElement(By.XPath("/html/body/button"));
    button.Click();
    IAlert a = driver.SwitchTo().Alert();
    if (a.Text.Equals("Press a button!"))
    {
        a.Accept();
    }
    else
    {
        a.Dismiss();
    }
}