Skeletons armed with melee weapons don't attack back other offenders except for players

i gave a skeleton diamond armor and a diamond sword, and spawned an iron golem and i wanted to watch the fight, i separated them by a one block wide wall so the golem attacks him and angers him, but the skeleton didn't do anything about it, he just kept looking at the golem and looked away, i tried this with other skeletons with each other, the melee one looks at the ranger that shot him as if he was shooting arrows, and ignores me and the other skeletons shooting him.
sorry i see no point of pictures because they won't do anything, a video would help but i don't have time to make one.