public void OldNullCheck() { var sharp = new OldSharp(); var address = sharp.GetCustomerStreetAddressById(1); Assert.That(address, Is.EqualTo("4 Crinan St.")); address = sharp.GetCustomerStreetAddressById(2); Assert.That(address, Is.Null); address = sharp.GetCustomerStreetAddressById(3); Assert.That(address, Is.Null); }