Coin Changer kata with Reduce using C# with MS Test

CoinChangerTests.cs

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace CoinChangerKata
{
    [TestClass]
    public class CoinChangerTests
    {
        [TestMethod]
        public void GivenNoCoins_WhenChangeForIsCalledWith0_ItMustReturnAnEmptyArray()
        {
            var target = new CoinChanger { Coins = null };
            Assert.IsFalse(target.ChangeFor(0).ToList().Any());
        }

        [TestMethod]
        public void GivenPennies_WhenChangeForIsCalledWith0_ItMustReturn0Pennies()
        {
            var target = new CoinChanger { Coins = new[] { 1 } };

            var expected = new[] { 0 };
            var actual = target.ChangeFor(0);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void GivenPennies_WhenChangeForIsCalledWith1_ItMustReturn1Penny()
        {
            var target = new CoinChanger { Coins = new[] { 1 } };

            var expected = new[] { 1 };
            var actual = target.ChangeFor(1);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void GivenNickels_WhenChangeIsCalledWith5_ItMustReturn1Nickel()
        {
            var target = new CoinChanger { Coins = new[] { 5 } };

            var expected = new[] { 1 };
            var actual = target.ChangeFor(5);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void GivenNickelsAndPennies_WhenChangeIsCalledWith5_ItMustReturn1Nickel0Pennies()
        {
            var target = new CoinChanger { Coins = new[] { 5, 1 } };

            var expected = new[] { 1, 0 };
            var actual = target.ChangeFor(5);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void GivenNickelsAndPennies_WhenChangeIsCalledWith7_ItMustReturn1Nickel2Pennies()
        {
            var target = new CoinChanger { Coins = new[] { 5, 1 } };

            var expected = new[] { 1, 2 };
            var actual = target.ChangeFor(7);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void GivenQuartersDimesNickelsAndPennies_WhenChangeIsCalledWith99_ItMustReturn3Quarters2Dimes0Nickels4Pennies()
        {
            var target = new CoinChanger { Coins = new[] { 25, 10, 5, 1 } };

            var expected = new[] { 3, 2, 0, 4 };
            var actual = target.ChangeFor(99);
            CollectionAssert.AreEqual(expected, actual);
        }
    }

    public class CoinChanger
    {
        public int[] Coins { get; set; }

        public int[] ChangeFor(int change)
        {
            if (Coins == null) return new int[] { };

            return Coins.Aggregate(
                new Tuple<int, IList<int>>(change, new List<int>()),
                (m, coin) =>
                {
                    var result = m.Item2;
                    result.Add(m.Item1 / coin);
                    return new Tuple<int, IList<int>>(m.Item1 % coin, result);
                }).Item2.ToArray();
        }
    }
}