What do you mean by testing an address? Why would you need to "test" it?
It has been speculated by many that MtGox lost the private keys to their cold cold storage wallets because of a bug in their key generation software.
Key generation is literally a few lines of code. It was tested in all programming languges from the begining of the bitcoin. Whoever ("many") speculated that, they don't know first thing about bitcoin. MtGox software may have had thousand bugs, but there's 0 chance key generation was one of them.