public void TestAdd()
{
var characteristics = new EditableCollection <Characteristic>();
var wrappedCharacteristics =
new WrappedEditableCollection <CharacteristicUsage, Characteristic>(characteristics);
characteristics.Add(new Characteristic());
wrappedCharacteristics.Count.Should().Be(characteristics.Count);
wrappedCharacteristics.First().Characteristic.Should().Be(characteristics.First());
var newCharacteristic = new Characteristic();
var newWrappedCharacteristic = new CharacteristicUsage(newCharacteristic);
wrappedCharacteristics.Add(newWrappedCharacteristic);
wrappedCharacteristics.Count.Should().Be(2);
wrappedCharacteristics.Count.Should().Be(characteristics.Count);
wrappedCharacteristics.First().Characteristic.Should().Be(characteristics.First());
wrappedCharacteristics.Last().Characteristic.Should().Be(characteristics.Last());
}