xcodebuild command has changed with xcode 5. Here is a script to run Unit tests :
Don't forget that schemes must be shared, you've got to create your Tests Scheme, Xcode 5 didn't create it for you
xcodebuild -workspace MyApp.xcworkspace -scheme myApp-Tests -destination=build -configuration Debug -sdk iphonesimulator7.0 ONLY_ACTIVE_ARCH=YES clean build test
Hope this helps :)