Deck shuffling puzzle: C# tester boilerplate

Shuffle.cs

public static class Shuffle
{
    static Random r = new Random();
    
    public static void swap(ref int a, ref int b)
    {
        if (a != b)
        {
            a ^= b;
            b ^= a;
            a ^= b;
        }
    }

    public static int rand(int min, int max)
    {        
        return r.Next(min, max + 1);
    }

    public static void shuffle(int[] deck)
    {
        //your code here
    }
}