By test it, do you mean see if the police show up at your door? If you know how it works, you just need a list of hashes and a way to find a collision which I believe exists.
Otherwise, you're really just highlighting the problem with all closed source software, you don't really have a way to check what it does so you have to trust the vendor.
We already know that a hash collision doesn't get far enough to involve police showing up at your door, so a full test would take something more substantial.
Otherwise, you're really just highlighting the problem with all closed source software, you don't really have a way to check what it does so you have to trust the vendor.