It's not a very well described example of the test. I've heard of this before but used to test for autism, and it was more something like "Bob puts his toy in a box and leaves, Alice takes his toy out of the box and hides it under a desk, when Bob comes back where does he go to grab his toy?"

The idea is if someone said "under the desk" they might not understand that people have different subsets of information, i.e. Bob wasn't there when Alice hid the toy, so he doesn't know it's not in the box where he left it until he checks himself.