Lately we have been incorporating select2-rails into our applications. I cannot say enough how much I love this tool and its ease of use.
That being said, we had had issues with testing and select2-rails. So Steve Tong of Rebel-Outpost spent some time and found a small script to use for testing it.
The only issue with this is that you can only have one option in the select2.
If anybody finds a better way, please let us know.