Wsrtjtyk

I'm testing a web UI using Selenium in Java. I've come to a test case where a button which links to another page is supposed to be clicked right after loading a new page.

However, sometimes when the button is clicked, no page redirect is triggered. I'm sure that the button gets clicked correctly, as the button animation triggers and selenium proceeds the test, where it fails because it doesn't find any elements that are supposed to be on the next page.

One possible workaround would be a Thread.sleep() before clicking the button, but I'd like to avoid this solution.

I've tried this workaround where I check if redirect happened, but this just causes the page to loop and never actually load.

while(!driver.getCurrentUrl().toLowerCase().endsWith("login/checkout")) {

    driver.findElement(By.cssSelector("button[data-checkout-url='/cart/checkout']")).click();

}

The button in question is this one, for example. However, this behaviour happens on multiple buttons.

<button class="btn btn-primary btn-block btn--continue-checkout js-continue-checkout-button"

   data-checkout-url="/cart/checkout">

   Checkout

</button>

The button is handled by javascript, however as I'm only testing the UI, I don't have deep knowledge of the system. The button normally only redirects you to login page.

However, sometimes when the button is clicked, no page redirect is
triggered. I'm sure that the button gets clicked correctly, as the
button animation triggers and Selenium proceeds the test, where it
fails because it doesn't find any elements that are supposed to be on
the next page.

To find a robust solution, there's probably no way around actually digging into the problem, and debugging the page to find out what exactly it normally does when the button is clicked, and why it fails in this case. Ideally, you'd want to test the page without knowing about its internals, but sometimes this is not possible.

While only debugging will truly tell you what is going wrong, I can offer an educated guess:

It seems that the page is performing additional initialization in the background after the visible part has loaded. For example, it might run JavaScript after loading which attaches event handlers to buttons. That means that there is a brief window of time after loading the page where it is not fully functional. If you hit that window during the test, weird things happen.

To correctly handle this, you will have to:

• find out what exactly is not yet "ready" in the page


• find something in the page that tells you the page is ready, such as a DIV appearing


• put code into your test (ideally into the Page Object, which you hopefully use) that waits for the page to be ready, typically using WebDriverWait
  

Unfortunately, the details of how to do this will depend on the page, so you'll have to do some digging (see above :-) ). Incidentally, this type of problem is not uncommon when testing complex web applications: Often the app will do something in the background after an action (such as a page load or a button click) has completed, and you will have to wait for the "real completion" before further interacting with the page.

One possible workaround would be a Thread.sleep() before clicking the
button, but I'd like to avoid this solution.

Yes, that is a workaround, and one I have actually used. It can be a pragmatic solution if the "proper" solution outlined above is too tedious, but as you probably know, it is not a reliable solution (you never know how long to wait), and if used frequently, will slow down your tests, so I see it as an option of last resort.

You can use wait.until() command to check the expected element is loaded and set maximum time to look for the element when you instantiate WebDriverWait()

 WebDriverWait wait = new WebDriverWait(driver, 10);

 wait.until(ExpectedConditions.or(

 ExpectedConditions.visibilityOfElementLocated(By.id("id1")),

 ExpectedConditions.visibilityOfElementLocated(By.id("id2"))

 ));