How to Test If a Building Is Properly Grounded Using Outlet or Panel Methods?

Hi,
I am not an Engineer but thought this would be the best place to ask this question. I work in AV Integration and had a customer with grounding issues. Upon further inspection of the ground outside, they found it had been pulled up and never re-installed. It was immediately installed when they found out about it.  When we plugged in testers, it showed proper grounding. I believe it was seeing the building as the ground, but the connection from the building to the ground was nonexistent. 

I have never seen a building without a ground, but would like to know if there is a test that can be performed from an outlet or panel that can tell me if the building is properly grounded? When I used the little cheap plug in teste  

Building grounds are for electrical safety. If done properly, it's a big stake that goes deep into the ground. There are testers available. Try Extech or Megger. Extech ground tester sells through Grainger for about $250. Here's an article from Megger that explains.https://uk.megger.com/electrical-tester/november-2007/a-guide-to-earth-testing

You can even confirm with your multimeter, just measure the voltage across Earth terminal in the socket and the neutral wire, It should not be as Zero Volt, and should not exceed more than 10V.