How to split testValues in test target only?

[sailypiotr]

Given this kind of code arrangement:

struct DependencyKeys {
    // MARK: - Tracking Keys
    
    enum TrackerKey: DependencyKey {}
    
    
    extension DependencyKeys.TrackerKey { static let liveValue: Trackable = GoogleTracker() }
 }

And if I would like to have the testValue in test target

extension DependencyKeys.TrackerKey {
    static var testValue: Trackable = TrackableMock()
}

I can not make it work, the library can't recognize this test value. How can I make it done?