Selenium: Too slow and to brittle for any decent size test suite. There's more on that if you wish.

Some javascript unit testing framework. I can't even remember the name. The syntax was ugly, the tests weren't easy to write, and the runner didn't integrate with any automated tools we used -- lame.

At RailsConf Europe , in the Q & A portion of my talk on Functional Testing someone asked what I recommend for testing Javascript.Ugh. Testing Javascript. Is it possible to recommend something when everything you've seen is terrible? Usually I'm cool with picking the tool that sucks the least, but when it comes to Javascript testing the only words that come to mind are: epic fail.In the past I've failed in two different ways.My response in Berlin was "The pivotal guys are smart, so if I were going to try something new it would be Screw Unit." Of course, I just googled and found the RubyForge project and two with the same name on GitHub. I'm sure one of those is the current trunk.A few days later it occurred to me what the correct answer was -- Don't use Javascript and you won't have to test it.No, I'm not suggesting that we should all go back to mostly static websites. Static content is fine for some things, but GMail is an obvious example of a site that is better done dynamically.However, Javascript isn't your only choice for highly dynamic websites.These days, if I were writing a website that required any dynamic interaction I would absolutely use Flex or Silverlight . I've done Flex, and it was nice to work with, but I must admit that I'm lured to Silverlight because it's going to (or does already?) support Ruby.I'm not sure what the Silverlight testing story is, but I found Flex (and ActionScript) to be quite testable. The single biggest win ( as I've said before ) is that I no longer need to do in-browser testing. Removing the browser from the equation is huge. No more IE bugs causing your tests to fail, no long start up times as the browser is run, etc.Testing with FlexUnit (with it's drawbacks) is an order of magnitude better than any experience I've had testing Javascript.I'm comfortable saying that I would still use Javascript for trivial features that provided so little business value that they did not warrant testing. However, any features that provide noticeable business value must be tested, and I would move to a RIA solution instead.In my experience, the benefits of switching to a RIA solution are dramatic, one of the largest being: you no longer need to worry about testing Javascript.