Fibonacci kata in C# using generators with .net core

Fibonacci.cs

using System.Collections.Generic;
using System.Linq;

namespace Library
{
    public static class Fibonacci
    {
        public static int Value(int n)
        {
            return Values(n).Last();
        }
        public static IEnumerable<int> Values(int n)
        {
            var x = 0;
            var y = 1;
            yield return x;
            yield return y;
            for(var i = 2; i <= n; i++)
            {
                var z = x + y;
                yield return z;
                x = y;
                y = z;
            }
        }
    }
}

FibonacciTests.cs

using Xunit;
using Library;
using System.Linq;

namespace Tests
{
    public class FibonacciTests
    {
        [Theory]
        [InlineData(1, 1)]
        [InlineData(2, 1)]
        [InlineData(3, 2)]
        [InlineData(4, 3)]
        [InlineData(14, 377)]
        [InlineData(20, 6765)]
        public void GivenValueItMustProduceExpected(int given, int expected) 
        {
            var actual = Fibonacci.Value(given);
            Assert.Equal(expected, actual);
        }

        [Fact]
        public void ValuesMustProduceTheFirst13FibonacciValues()
        {
            var expected = new [] {0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144};
            var actual = Fibonacci.Values(12);
            Assert.Equal(expected, actual);
        }
    }
}

Based on http://geekswithblogs.net/BlackRabbitCoder/archive/2010/04/21/more-fun-with-c-iterators-and-generators.aspx