Automated tests with Selenium: how to close alert-Windows? - multithreading

Question

Excecuting an automated test on a website with selenium I was faced with this problem, that somewhere on the website, when my test changes the selection of a DropDownList, an alert-window is thrown asking "are you sure you want to leave this page".
The root problem is the refreshing times of the page. When I look for an element:
Select sortingDropDownlist= new Select(webdriver.findElement(By.id("sortView")));
it takes some time for the page to be refreshed, even if I hav not changed anything. In this case a thread.sleep(500) would help preventing an alert to be poped out.
After a change to the DropDownList:
sortingDropDownlist.selectByValue("alpha");
the onchange-javascript behind the list tries to reload the page, while my test is continuing to the Then-part verificating the new value. The test stucks there until someone manually closes the alert window. I get the error:
org.openqa.selenium.WebDriverException: unknown error: cannot determine loading status
from unexpected alert open
(Session info: chrome=53.0.2785.116)
(Driver info: chromedriver=2.21.371459 (36d3d07f660ff2bc1bf28a75d1cdabed0983e7c4),platform=Windows NT 6.3 x86_64) (WARNING: The server did not provide any stacktrace information)
Command duration or timeout: 43 milliseconds
Build info: version: '2.53.1', revision: 'a36b8b1', time: '2016-06-30 17:37:03'
System info: host: 'de-adn-bfxqp72', ip: '192.168.99.1', os.name: 'Windows 8.1', os.arch: 'amd64', os.version: '6.3', java.version: '1.8.0_91'
Driver info: org.openqa.selenium.chrome.ChromeDriver
Capabilities [{applicationCacheEnabled=false, rotatable=false, mobileEmulationEnabled=false, chrome={chromedriverVersion=2.21.371459 (36d3d07f660ff2bc1bf28a75d1cdabed0983e7c4), userDataDir=C:\Users\javadieh\AppData\Local\Temp\scoped_dir11488_27974}, takesHeapSnapshot=true, databaseEnabled=false, handlesAlerts=true, hasTouchScreen=false, version=53.0.2785.116, platform=WIN8_1, browserConnectionEnabled=false, nativeEvents=true, acceptSslCerts=true, locationContextEnabled=true, webStorageEnabled=true, browserName=chrome, takesScreenshot=true, javascriptEnabled=true, cssSelectorsEnabled=true}]
Session ID: b6e2d6fec84269128a420809f929916d
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
...
An easy but dirty solution is again to Thread.sleep(500) directly after changing the selection. But I have a bad feeling using thread.sleep. So I am looking for a good solution.
I also tried this solution: in a seperate thread waiting for an alert window to appear, switch to it and close it.
But... although the alert window ist there my thread does not find it. It is not a matter of time out. Here ist my thread's code:
public class AlertChecker extends Thread {
WebDriver webdriver=null;
WebDriverWait wait;
public AlertChecker(WebDriver webdriver) {
super();
this.webdriver = webdriver;
wait = new WebDriverWait(webdriver, 10);
}
public void run(){
System.out.println("MyThread running");
try {
wait.until(ExpectedConditions.alertIsPresent());
System.out.println("alert found");
Alert alert = webdriver.switchTo().alert();
alert.accept();
} catch (Exception e) {
//exception handling
System.out.println(e);
}
System.out.println("MyThread stopping");
}
}
How can I wait for the page to be refreshed?
Thanks.

Answer 1

If you are getting a JavaScript Alert please use the below code.
public static void isAlertpresent(WebDriver driver)
{
try
{
Alert window = driver.switchTo().alert();
String content = window.getText();
window.accept();
System.out.println("Alert Appeared & handeled : "+content );
}
catch (Exception e)
{
System.out.println("No Alert Appeared");
}
}
call this method from where you suspect the Alert is appearing as below,
isAlertpresent(driver);
If its not a JavaScript Alert, try Window handling techniques to handle the alert.