My view on the question whether the omniscience, omnipotence and omnipresence of the Guru or Preceptor should be tested since the Guru is equated to God with those qualities.
"I would ask a question. Is such a test ever necessary?
Guru is not the earthly body we just imagine.
That body will stink if it does not take bath and would laugh cry and swear.
But guru is the core or kernel present somewhere which the disciple tries to relate to a mortal body.
Once the guru is accepted as the guide and guardian, his real presence is through things for which he exists and a working residence for him is created in our hearts.
There the essence of the guru resides ever guiding us with all the three omni qualities omniscience, omnipresence and omnipotence.
For god too if you try to see Him in a stone or statue and not in spirit no omni qualities can be there.