public void Should_decrypt_the_property_correctly() { var message = new MessageWithIndexProperties { Secret = Create() }; message[0] = "boo"; message[1] = "foo"; mutator.MutateIncoming(message); Assert.AreEqual("boo", message[0]); Assert.AreEqual("foo", message[1]); Assert.AreEqual(MySecretMessage, message.Secret.Value); }