When having the gamerule doMobSpawning set to false, shulkers still spawn in End Cities. I believe this is a bug as Shulkers should be classed as (hostile) mobs and therefore not spawn naturally while the gamerule is set to false.
What I expected to happen was...:
No shulkers would be present in the End Cities.
What actually happened was...:
Shulkers still spawned in the End Cities even though doMobSpawning was set to false.
Steps to Reproduce:
Set the doMobSpawning gamerule to false by typing the following in the chat: /gamerule doMobSpawning false
Then visit one of the End Cities.
Shulkers do not spawn. They are generated with the terrain, like passive mobs.