operator== with null check 2, C#

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using System;

namespace Rextester
{
    class TestClass
    {
        public TestClass(int val)
        {
            this.SomeProp = val;
        }

public int SomeProp { get; set; }

public override bool Equals(object obj)
        {
            if (obj == null)
            {
                return false;
            }

if (!(obj is TestClass))
            {
                return false;
            }

TestClass testClass_other = (TestClass)obj;

return (this == testClass_other);
        }

public override int GetHashCode()
        {
            return this.SomeProp.GetHashCode();
        }

public static bool operator ==(TestClass test1, TestClass test2)
        {
            bool oneNull = Object.ReferenceEquals(test1, null) ^ Object.ReferenceEquals(test2, null);
            bool bothNull = Object.ReferenceEquals(test1, null) && Object.ReferenceEquals(test2, null);

if (oneNull)
            {
                return false;
            }

if(bothNull)
            {
                return true;
            }

return test1.SomeProp == test2.SomeProp;
            
        }

public static bool operator !=(TestClass test1, TestClass test2)
        {
            return !(test1 == test2);
        }

public override string ToString()
        {
            return "SomeProp=" + this.SomeProp;
        }
    }

public class Program
    {
        static void DoTest(TestClass a, TestClass b)
        {
            string aString;

if(a == null)
            {
                aString = "(null)";
            }
            else
            {
                aString = a.ToString();
            }

string bString;
            if(b == null)
            {
                bString = "(null)";
            }
            else
            {
                bString = b.ToString();
            }

if (a == b)
            {
                Console.WriteLine("[EQUAL] a = " + aString + " b = " + bString);
            }
            else
            {
                Console.WriteLine("[NOT EQUAL] a = " + aString + " b = " + bString);
            }
        }

public static void Main(string[] args)
        {
            TestClass a = new TestClass(8);
            TestClass b = new TestClass(9);
            TestClass aka_a = new TestClass(8);

DoTest(a, b);
            DoTest(a, aka_a);
            DoTest(a, a);
            DoTest(null, null);
            DoTest(null, a);
            DoTest(a, null);

}
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,26 sec, absolute running time: 0,11 sec, cpu time: 0,09 sec, average memory usage: 13 Mb, average nr of threads: 2, absolute service time: 0,41 sec