public void AddDeliveryReceiverTest() { var fakeDeliveryReceiverOne = new DeliveryReceiver(); var fakeDeliveryReceiverTwo = new DeliveryReceiver(); M.AddDeliveryReceiver(fakeDeliveryReceiverOne); Assert.AreEqual(1, DeliveryReceivers.Instance.Count); M.AddDeliveryReceiver(fakeDeliveryReceiverTwo); Assert.AreEqual(2, DeliveryReceivers.Instance.Count); }