C# is Pass-By-Value by default proof

PassByValueProofTests.cs

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

namespace Framework.Tests.General
{
    [TestClass]
    public class PassByValueProofTests
    {
        public class SomeClass
        {
            public SomeClass(String value)
            {
                SomeValue = value;
            }
            
            public String SomeValue {get;}
        }
	    
        public void PassByValue(SomeClass s)
        {
            s = new SomeClass("Hello World");
        }
	    
        public void PassByRef(ref SomeClass s) //ref is only difference
        {  
            s = new SomeClass("Hello World");            
        }

        [TestMethod]
        public void ByRef()
        {
            SomeClass c = new SomeClass("Hello");
            PassByRef(ref c);

            Assert.AreEqual("Hello World", c.SomeValue);
        }

        [TestMethod]
        public void ByValue()
        {
            SomeClass c = new SomeClass("Hello");
            PassByValue(c);

            Assert.AreEqual("Hello", c.SomeValue); //this is different result, because "ref" is not implicit
        }
    }
}