selenium tips

Hello Readers, Welcome Back !!

As the first part of this Selenium Tips series, this article intends to summarize the different ways to interact with dynamic sites that refresh content asynchronously wherein the script will have to wait for certain elements to appear or disappear before proceeding further. As you are already aware of, Selenium has several ‘waitFor’ commands that fulfill this purpose. waitForCondition is one among them. ‘waitForCondition’ basically takes in two arguments, a JavaScript snippet and a timeout period in milliseconds. The snippet is executed either until it returns true or until the timeout period, after which the command will return an error. Now enough of theory and let’s get into action.

Example:
Variation 1:
Consider the following example where there are two drop-downs, one for the states and the other for counties.
The county drop-down is populated based on the state selection.

(Example courtesy of bitrepository.com)

You can see in the site above, when the state is selected, a spinner shows up for a few seconds before the county drop-down is populated. Using waitForCondition and some JavaScript, we wait until display style attribute changes to ‘none’ in the snippet below.

selenium.open("http://www.bitrepository.com/apps/viewDemo/?originalPost=http://www.bitrepository.com/dynamic-dependant-dropdown-list-us-states-counties.html&demoPage=http://www.bitrepository.com/demo/dynamic-dependent-dropdown-list/");
selenium.selectFrame("mainFrame");
selenium.select("state", "label=California");
selenium.waitForCondition("var value = selenium.browserbot.findElementOrNull('loading_county_drop_down'); value.style.display == 'none'", "10000");
selenium.select("county", "label=Amador County");

Variation 2:
You may also use logical operators to add additional logic.

selenium.waitForCondition("var value = selenium.browserbot.findElementOrNull('loading_county_drop_down'); value.style.display == 'none' || selenium.browserbot.getUserWindow().document.form.county.options[0].text == 'Select a county of California';", "10000");

Variation 3:
The same can also be accomplished by simply using waitForNotVisible and/or waitForSelectOptions.

selenium.waitForNotVisible("loading_county_drop_down");
selenium.waitForSelectOptions("county","regexpi:Amador County");

You may wonder why you need to go into the trouble of using complex JavaScript with waitForCondition while you can accomplish the same with one of the other selenium waitFor commands. The additional advantage of using waitForCondition is that you are able to declare a timeout value explicitly whereas the other waitFor commands simply honor the default selenium timeout value.

Other useful variations:
You may have seen many AJAX intensive sites displaying a ‘Loading..’ or ‘Saving..’ or ‘Processing…’ message when a button or a link is clicked. In such cases you may find this to be helpful to wait for the status text to change or disappear.

Assuming that a ‘Saving’ message is displayed within a div tag when a fictional ‘Save’ button is clicked in the snippet below:

selenium.waitForCondition("var value = selenium.getText(\"//div[@class='save-text']\");value != \"Saving\"", "20000");

In general, .Net sites that use the web form controls, panel controls etc, trigger an asynchronous postback everytime a form control is filled or a .Net tab or panel control is clicked etc. In such cases, I’ve found the following to be very helpful in waiting for the postback to complete.

selenium.waitForCondition("selenium.browserbot.getUserWindow().Sys.WebForms.PageRequestManager.getInstance().get_isInAsyncPostBack() == false;", "10000");

Now for the killer part, for sites that use jQuery, if all you need is to confirm there aren’t any active asynchronous requests, then the following does the trick:

selenium.waitForCondition("selenium.browserbot.getUserWindow().$.active == 0", "10000");

As you can see, there are several possible variations to a single command. The possibilities are endless with Selenium.

Happy Testing !!

 

 

Posted by Anu Sandhanam at 5:02 pm

5 Responses to “Selenium Tips – Wait with WaitForCondition”

1. A Smattering of Selenium #45 « Official Selenium Blog says:

   March 28, 2011 at 4:15 am

   [...] Wait with WaitForCondition discusses some advanced synchronization tricks [...]
2. Daniel Would says:

   March 29, 2011 at 2:17 am

   One problem I found with WaitforCondition is that every error ends up looking the same. timeout. and people always wonder, was the timeout because it was slow? or because it was actually broken?

   I have started using a custom wrapper around waitForCondition that slices the wait time up into 500ms blocks, and each loop round checks for known failure conditions. Eg I might want to allow up to 20 seconds for something to appear, but if I hit an exception page I want to know as soon as that happens, not after 20 seconds.
   So my custom wrapper checks for a couple of ‘known’ failure indicators allowing us to fail fast but give the benefit of a longer wait on simply slow but working system.
3. Introducing Selenium 2 / WebDriver Support » The BrowserMob Blog says:

   July 7, 2011 at 8:43 am

   [...] applications will be in upcoming articles but in the meantime check out the following Selenium tip: Wait with WaitForCondition. Posted by Ben Jones at 8:43 am Tagged with: Selenium [...]
4. In the Driver’s Seat: Load Testing Best Practices–Scripting | Webmetrics Blog says:

   August 8, 2011 at 3:51 am

   [...] page loads which can be accomplished by the solution proposed in this article. The article on waitForCondition may also make an interesting read to learn more about advanced handling of [...]
5. Repost: In the Driver’s Seat: Load Testing Best Practices – Scripting » The BrowserMob Blog says:

   August 8, 2011 at 3:51 am

   [...] page loads which can be accomplished by the solution proposed in this article. The article on waitForCondition may also make an interesting read to learn more about advanced handling of [...]

 http://blog.browsermob.com/2011/03/selenium-tips-wait-with-waitforcondition/