Coin Changer kata with Map in C# using MS Test

CoinChangerTests.cs

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

namespace CoinChanger
{
    [TestClass]
    public class CoinChangerTests
    {
        [TestMethod]
        public void GivenZeroWithNoCoins_ItMustReturnEmptyArry()
        {
            var changer = new CoinChanger();
            var actual = changer.ChangeFor(0);
            Assert.AreEqual(0, actual.Length);
        }

        [TestMethod]
        public void GivenZeroWithPennies_ItMustReturnEmptyArry()
        {
            var changer = new CoinChanger { Coins = new[] { 1 } };
            var expected = new[] { 0 };
            var actual = changer.ChangeFor(0);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given1WithPennies_ItMustReturn1Penny()
        {
            var changer = new CoinChanger { Coins = new[] { 1 } };
            var expected = new[] { 1 };
            var actual = changer.ChangeFor(1);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given2WithPennies_ItMustReturn2Pennies()
        {
            var changer = new CoinChanger { Coins = new[] { 1 } };
            var expected = new[] { 2 };
            var actual = changer.ChangeFor(2);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given5WithNickels_ItMustReturn1Nickel()
        {
            var changer = new CoinChanger { Coins = new[] { 5 } };
            var expected = new[] { 1 };
            var actual = changer.ChangeFor(5);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given6WithNickelsAndPennies_ItMustReturn1NickelAnd1Penny()
        {
            var changer = new CoinChanger { Coins = new[] { 5, 1 } };
            var expected = new[] { 1, 1 };
            var actual = changer.ChangeFor(6);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given7WithNickelsAndPennies_ItMustReturn1NickelAnd2Pennies()
        {
            var changer = new CoinChanger { Coins = new[] { 5, 1 } };
            var expected = new[] { 1, 2 };
            var actual = changer.ChangeFor(7);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given13WithDimesNickelsAndPennies_ItMustReturn1Dime0NickelsAnd3Pennies()
        {
            var changer = new CoinChanger { Coins = new[] { 10, 5, 1 } };
            var expected = new[] { 1, 0, 3 };
            var actual = changer.ChangeFor(13);
            CollectionAssert.AreEqual(expected, actual);
        }

        [TestMethod]
        public void Given99WithQuartersDimesNickelsAndPennies_ItMustReturn3Quarters2Dime0NickelsAnd4Pennies()
        {
            var changer = new CoinChanger { Coins = new[] { 25, 10, 5, 1 } };
            var expected = new[] { 3, 2, 0, 4 };
            var actual = changer.ChangeFor(99);
            CollectionAssert.AreEqual(expected, actual);
        }
    }

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

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

            return Coins.Select(coin =>
            {
                var result = amount / coin;
                amount %= coin;
                return result;
            }).ToArray();
        }
    }
}