Spider's wikia page says in the history at 1.9 "Spiders can draw line of sight through blocks again." But obviously they actually can't.
I haven't tested it in any other versions than 1.10.2.
MC-106421
Spiders can't detect players through walls
Resolved
Duplicate
0
It's WAI per MC-66806.
Wiki is not an official source, so, it can contain mistakes.
Also, if you look here (a version, in which this was "added"), you'll see info about MC-87946, which is now fixed.