Simple difference not detected

[wexman]

Hi,
I have a simple use case here and unfortunately it doesn't work as expected. Here's a unit test that's failing although I think it shouldn't:

    using EntityChange;
    using NUnit.Framework;

    [TestFixture]
    public class DesiredStateChecks
    {
        public abstract class AbstractBase
        {
        }

        public class ConcreteClass: AbstractBase
        {
            public string SomeString { get; set; }
        }

        public class Consumer
        {
            public AbstractBase SomeProperty { get; set; }
        }
        
        [Test]
        public void Foo()
        {
            var obj1 = new Consumer()
            {
                SomeProperty = new ConcreteClass()
                {
                    SomeString = "Test1"
                }
            };
            var obj2 = new Consumer()
            {
                SomeProperty = new ConcreteClass()
                {
                    SomeString = "Test2" // that's a difference!
                }
            };

            var comparer = new EntityComparer();
            var result = comparer.Compare(obj1, obj2);
            Assert.That(result, Is.Not.Empty);
        }
    }

Am I using it wrong?