I was playing with selenium to try testing a web app I work on earlier today, but ran into the following error pretty much straight away…

input [error] Unexpected Exception: message ->
  element.ownerDocument.createEventObject is not a function
...

From a bit of digging, it looks like the current version of Selenium (0.8.3 as of Jan 15, 2008) isn’t compatible with mootools.

The mootools forums have a fairly simple patch to fix the issue.

Apparently Selenium is checking for the fireEvent method, normally only available in IE, but which mootools adds to other browsers. As a result, mootools thinks it’s running in IE, and tries to call createEventObject, which really is only available in IE.

Having made it over that hurdle, selenium is looking like quite a nice tool.