https://exercism.io/tracks/csharp/exercises/hello-world/solutions/61b585c8b50645739dd179335a4b0c17

HelloWorld.cs

using System;

public class HelloWorld
{
    private const string Greetings = "Hello, World!";

    public string Hello()
    {
        return Greetings;
    }
}

HelloWorldTest.cs

using Xunit;

public class HelloWorldTest
{
    [Fact]
    public void Say_hi_()
    {
        Assert.Equal("Hello, World!", HelloWorld.Hello());
    }
}