public void VerifyInvestorsRemovedFromSubscriberList()
        {
            // Arrange
            var utstock    = new StockUnitTestCaseExtension("TestStock", "TEST", 10.00);
            var utinvestor = new UnitTestInvestor()
            {
                InvestorId = 1,
                Name       = "TestInvestor"
            };

            utstock.Attach(utinvestor);

            //Act
            utstock.Detach(utinvestor);

            //Assert
            Assert.AreEqual(0, utstock.Investors.Count);
        }