Sequence/CardUtility.cs

using Sequence.Entities;

public static class CardUtility
{
    public static readonly IDictionary<int, string> faceCardMap = new Dictionary<int, string>
    {
        [11] = "J",
        [12] = "Q",
        [13] = "K"
    };

    public static ICollection<Card> GenerateDeck()
    {
        var cards = new List<Card>();
        var suits = Enum.GetValues<Suit>();

        foreach (var suit in suits)
        {
            for (var i = 1; i <= 10; i++)
            {
                cards.Add(new Card
                {
                    Id = Guid.NewGuid(),
                    Suit = suit,
                    Value = i.ToString()
                });
            }

            foreach (var faceCard in faceCardMap)
            {
                cards.Add(new Card
                {
                    Id = Guid.NewGuid(),
                    Suit = suit,
                    Value = faceCard.Value
                });
            }
        }

        return cards;
    }
}