FizzBuzz kata in C# using LINQ and "infinite" list.

FizzBuzzerTests.cs

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

namespace FizzBuzz
{
    [TestClass]
    public class FizzBuzzerTests
    {
        private static void AssertThat(string expected, int value)
        {
            Assert.AreEqual(expected, FizzBuzzer.ValueOf(value));
        }

        private static void AssertContainsFizz(int value)
        {
            AssertContains(value, "Fizz");
        }

        private static void AssertContainsBuzz(int value)
        {
            AssertContains(value, "Buzz");
        }

        private static void AssertContains(int value, string expected)
        {
            Assert.IsTrue(FizzBuzzer.ValueOf(value).Contains(expected));
        }

        [TestMethod]
        public void GivenNumberNotDivisibleBy3Or5_ItMustReturnSelfAsString()
        {
            AssertThat("2", 2);
            AssertThat("4", 4);
            AssertThat("22", 22);
            AssertThat("44", 44);
        }

        [TestMethod]
        public void Given3_ItMustReturnFizz()
        {
            AssertThat("Fizz", 3);
        }

        [TestMethod]
        public void GivenNumberDivisibleBy3_ResultMustContainFizz()
        {
            AssertContainsFizz(3);
            AssertContainsFizz(9);
            AssertContainsFizz(33);
            AssertContainsFizz(333);
        }
        
        [TestMethod]
        public void Given5_ItMustReturnBuzz()
        {
            AssertThat("Buzz", 5);
        }

        [TestMethod]
        public void GivenNumberDivisibleBy5_ResultMustContainBuzz()
        {
            AssertContainsBuzz(5);
            AssertContainsBuzz(25);
            AssertContainsBuzz(55);
            AssertContainsBuzz(555);
        }

        [TestMethod]
        public void Given15_ItMustReturnFizzBuzz()
        {
            AssertThat("FizzBuzz", 15);
        }


        [TestMethod]
        public void GivenNumberDivisibleByBoth3And5_ItMustReturnFizzBuzz()
        {
            AssertThat("FizzBuzz", 30);
            AssertThat("FizzBuzz", 45);
            AssertThat("FizzBuzz", 15000);
        }
    }

    public class FizzBuzzer
    {
        public static string ValueOf(int n)
        {
            var fizzes = Enumerable.Range(0, int.MaxValue).Select(s => s%3 == 0 ? "Fizz" : string.Empty);
            var buzzes = Enumerable.Range(0, int.MaxValue).Select(s => s%5 == 0 ? "Buzz" : string.Empty);

            var result = fizzes.Zip(buzzes, (f, b) => f + b)
                .Zip(Enumerable.Range(0, int.MaxValue).Select(s => s.ToString()),
                (fb, d) => string.IsNullOrEmpty(fb) ? d : fb);

            return result.Skip(n).First();
        }
    }
}