QSettings custom class serialization problem

[fullmetalcoder]

Is it normal?

Yes.

How can I correctly serialize that Test2 instance?

In this case, it would be fairly easy to tweak the code to serialize properly but a lot more annoying to deserialize. Basically you'd have to move the serialization code to a virtual method of Test and the deserialization to some kind of factory. To distinguish between serialization of different types you'd then need to prefix the serialized data with a id (unique to each supported class).