[TestClass]
    public class UnitTest1
    {
        [TestMethod]
        public void TestMethod2()
        {
            IDerived derivedActual = new Derived { Dependency = new Dependency() };
            IBase baseActual = derivedActual;

            Assert.IsNotNull(derivedActual.Dependency); //passes
            Assert.IsNotNull(baseActual.Dependency); //passes
        }
    }

    public interface IDerived : IBase
    {
        new IDependency Dependency { get; }
    }

    public interface IBase
    {
        IDependency Dependency { get; }
    }

    public interface IDependency
    {
    }

    class Derived : IDerived
    {
        public IDependency Dependency { get; set; }
    }

    class Dependency : IDependency
    {
    }