class CardGame {
    private let deck: Deck
    private let randomizer: Randomizer

    init(deck: Deck, randomizer: Randomizer = DefaultRandomizer()) {
        self.deck = deck
        self.randomizer = randomizer
    }

    func drawRandomCard() -> Card {
        let index = randomizer.randomNumber(upperBound: deck.count)
        let card = deck[index]
        return card
    }
}