They do internal testing too, I should image they have been playing with auto-attack for a while now in the studio, working on it as well. it's not like the separate teams do different parts of the game then throw it all together for the patch last second. Most studios work with a file managing system over a network, so everyone's kept up-to-date while they work. To think that they are making content for the auto-attack system without actually having the auto-attack system for themselves is ridiculous.