Can MacBook Pro with Retina display (13", Late 2012) output above 1080p to 4k tv?
What's officially "supported" and what's possible don't match. I have a late-2012 rMBP and got 4K out of it at 30Hz.

I took a screenshot as proof: 

Just a normal mini-displayport&lt;->displayport cable was used.

More details in my answer here: https://apple.stackexchange.com/a/147765/39878

or on this blog post: http://www.mattburns.co.uk/blog/2014/09/30/running-the-4k-aoc-u2868pqu-and-intel-hd4000-graphics/