It needs to get set once, in terms of objc test suites the first one ran is the first alphabetically so unless you're adding an `@implementation AAUtilties` kind of thing putting something like this in the top of the first test suite that you need to use it in makes some sense. 

Other option is to say superfluously that it's worth adding to every file to ensure no-one gets it wrong but it isn't very DRY. 

Agree on wording though.