Why shouldn't they count? It's literally testing a nuclear weapon. The clock does not say: "Time since the last detonation of a nuclear weapon".

Edit: But one could argue that nuclear weapons get tested all the time without any kind of detonation. These should count too IMHO.

Edit: just read another article on the tests. They happen to design new weapons with them which makes them not tests to see if the nukes still work like I thought.