How to write the Unit Test for static functions?

unit-test-static-func

import Foundation
import AppTrackingTransparency
import PlaygroundSupport

protocol PrivacyManagerBridge {
    static func requestTrackingAuthorization(completionHandler completion: @escaping (ATTrackingManager.AuthorizationStatus) -> Void)
}

extension ATTrackingManager: PrivacyManagerBridge {}

protocol AppPrivacyManagerContract {
    func requestTrackingAuthorization(completionHandler completion: @escaping (ATTrackingManager.AuthorizationStatus) -> Void)
}

class AppPrivacyManager: AppPrivacyManagerContract {
    private var trackable: PrivacyManagerBridge.Type!

    init(trackable: PrivacyManagerBridge.Type = ATTrackingManager.self) {
        self.trackable = trackable
    }

    func requestTrackingAuthorization(completionHandler completion: @escaping (ATTrackingManager.AuthorizationStatus) -> Void) {
        self.trackable.requestTrackingAuthorization(completionHandler: completion)
    }
}

class ATTrackingManagerMock: PrivacyManagerBridge {
    static func requestTrackingAuthorization(completionHandler completion: @escaping (ATTrackingManager.AuthorizationStatus) -> Void) {
        // Return whichever flow you want to test.
        completion(.denied)
    }
}

let privacyManager = AppPrivacyManager(trackable: ATTrackingManagerMock.self)
privacyManager.requestTrackingAuthorization { result in
    // result here
}

PlaygroundPage.current.finishExecution()