[WIP] Studio library view tests

@dragonfi the problem here is that it depends on two implementation details:

* `_replace` method
* the fact that `_replace` returns a copy of an object, rather than modifies the object itself

This could or could not change in foreseable future (at least both are documented :)). So, again, there's a tradeoff between not using "private" methods and having a bit of duplicated code. I'm fine with whatever decision you make.