In the Xcode preferences, there's a section for Behaviors where you can specify how Xcode should handle certain situations. What I learned about today was that you can have Xcode tell you when your tests pass or fail:
Here I have told Xcode to use the Good News voice to announce when my tests pass. I also picked a voice for passing tests: Bad News seemed appropriate.
Comes in handy when you have switched to another application and you happened to miss the notification in the corner of the screen. Plus, it sounds cool.
h/t Leo PicadoTweet