To install Go mode for emacs check this stack response http://stackoverflow.com/questions/1715464/emacs-lisp-mode-for-go
Go-koans have Emacs function to speed up koans resolvig. Simply put go-koans.el file somewhere in your load-path
and then
(require 'go-koans)
into your init.el file (helper integrates with great Expand region extension from magnars: https://github.com/magnars/expand-region.el)
next cd into your koans directory, open some go file and press C-c C-r - Emacs will open file and goto line where error occurs
If your code failed you can see at *go-koans* buffer there will be shell output from go test command