no way to know
Given that it's over 40 years since any major power has tested a nuclear SYSTEM (i.e. put a bomb on a missile, fired it, got to the target and have it detonate) it's not unreasonable to say that none of the nuclear weapons we have today have ever been fully tested. Letting one off in an underground facility doesn't simulate the rigours of launch/space-travel, so there's no way to know if the device would work - or detonate, or fail due to adverse conditions whilst in flight.
Even worse is that with the passing of time, all the engineers and designers who gained experience from the "live" tests are now either dead or retired. The people working on nukes today learned their trade second-hand from the people who actually blew things up. If they're new to the industry, their knowledge and experience is probably third-hand.
While you can run some intensive computer programs to simulate the explosion and even the aging process inside a device, you're limited to simulating things you know about and can test in the real world. Will a nuclear device detonate if someone hit it in many places simultaneously? We'll never know, but I personally don't ever want to give one a kick, to find out.