Ext JS blog has a post about testing web application with Selenium. It provides quick overview of Selenium and gives instructions how to set it up. For me the most interesting part of the article was the example Selenium test case code.
At work we have been using Selenium to create acceptance tests for Ext GWT application and it has been quite painless so far. In our case the most important factor was to set id's for fields we wanted to test. That makes locating the right field in Selenium much easier. Another issue was the right mouse click because the application has some contextual menus. The Selenium IDE does not register right clicks properly so it was necessary to modify those actions manually to use mouseUpRightAt.
Yesterday I was wondering how to handle Ext GWT DateField's date picker in Selenium test and I ended up typing the date value in the field instead of clicking the calendar icon. After mentioning this to my colleague he told me to check the blog entry above. From the example I learnt about /following-sibling::img. It seems to be the way to handle trigger fields nicely - something to try out next week.