Behaviour of a test page B which is a child of a test page A?

A test page "B" is the child of test page "A". If "A" is tested than always "B" gets tested as well. 

So "A" behaves like a suite page.

Not sure if this is a bug or a feature. 
But I am quit sure this behaviour was different in older versions.

The behaviour can stay like this for me. But want to be sure that it will stay like this before I start using it.