For unit testing public classes of my main app target in my swift unit tests, I have to import my main app module in my tests like so:
#import MyAppModuleName<
You were almost there, you just need to update the iOS Deployment Target for your Project and both of your targets.
For your project:
For your app target:
For your test target:
You should probably do a clean and rebuild, no need to restart Xcode. I guess this will also work if you want to target 8.1 etc.