Here's my little user story:
As a blogger,
I want to use Threely as my url shortener.
So that I get more letters on Twitter.
Pretty simple story, and also very simple to implement, but impossible to test? I can certainly test the API to twitter, but given I use a wordpress plugin (developed by someone else) to do the auto-posting is it worth the effort for the addition of 6 lines of code?
For me, the pragmatic solution is to take the risk based approach. I'm going live with Threely (http://3.ly) (again, fixed a small typo), but have an escape plan (extremely important when there are known risks) which is the ability to revert if anything untowards happens and revisit my approach.
So, here goes, pressing the big red button