Create unit tests for the analytical module

Develop a set of unit tests for the AppAnalytics class. You may extend the EventTracker class if desired.

final class EventTracker {
    private init() {}

    static let shared = EventTracker()

    func track(event: String) {
        print("Event \(event)")
    }
}

/// -----

final class AppAnalytics {
    func trackScreen() {
        EventTracker.shared.track(event: "Screen")
    }
}