class NetworkManager {
    // Stores the session used in this class
    private let session: URLSession

    // Dependency Injection + default argument for normal initializ
    init(session: URLSession = .shared) {
        self.session = session
    }

    func loadData(from url: URL,
                  completionHandler: @escaping (NetworkResult) -> Void) {
        let task = session.dataTask(with: url) { data, _, error in
            let result = data.map(NetworkResult.success) ?? .failure(error)
            completionHandler(result)
        }

        task.resume()
    }
}