Did he testify that he saw the gun?
he did testify that he saw the gun yes.
unrelated to your post - i love how people just keep inventing things that happened as if there isnt a video we can now watch and see exactly what happened.
he didnt scream at him multiple times, he didnt tell him to stop reaching for his pockets... the cops voice is pretty calm and normal speaking volume when he says "dont reach for it then, dont pull it out" both of them reply fairly calmly that he isnt going to pull it out, then one second later the cops voice is only very slightly elevated when he repeats "dont pull it out" and then less than a second later he opens fire.
it is sort of ironic that the cop only started screaming after the threat was eliminated. well, the imaginary threat.
but he told him not to move! no, he didnt.
but he screamed at him to stop! no, he didnt.
if the cop did what he was trained to do this never happens, philando castile was being cooperative and polite, if he was told to stop and put his hands on the wheel immediately i have no doubt he would have done just that.