Yup, from what I read it isn't uncommon for PBX installers and such to plan test calls with 911. The 911 center understand that such testing is important for public safety and usually provides some way to handle it.
I'd think that a carrier would be able to implement such testing without even bothering the 911 center. Presumably they could redirect the call from a specific device/tower/etc to someplace else. They could even stick the phone in a Faraday cage with a microcell to test it.