When Flex first came onto the scene back in 2004, we loved it but something was missing. How do we test our applications? There were no real solutions at the time, but with the release of Flex 2 (in 2006) we were given FlexUnit (similar to JUnit in the Java world) and also QuickTest Pro (QTP) added support for web applications built in Flex. With QTP would record actions and then play them back and set checkpoints along the way. I've used QTP, but it is not as user-friendly as I would want it to be, so I've been looking and waiting to see what other testing applications would pop up.
And recently I've discovered two other solutions, so perhaps you will want to take a look as well.
This testing tool has been around for while and is used for testing traditional web applications. But recently an add-on has been created to support the testing of Flex applications as well. You can get the add-on here.
This is perhaps my favorite so far. It was built specifically for testing Flex (and AIR) applications, its scripting language is easy to understand and you don't need to compile your application in any special way for it work (unlike QTP). I'm just waiting for the next release before using it on my own applications, cause I'm waiting for certain bugs to be fixed.
So obviously the automated testing tool support for Flex is definitly improving, I've also heard that SilkTest will be supporting Flex in the future as well.
What do you guys use?