*.go vs *_test.go, Run Go checks similar to Syntastic, but with async.

vimrc

let g:neomake_go_gotest_maker = {
	\ 'exe': 'go',
	\ 'args': ['test', '-c'],
	\ 'errorformat': 
		\ '%f:%l: %m,' .
		\ '%-G#%.%#'
	\ }
au BufEnter *_test.go let g:neomake_go_enabled_makers = ['gotest']
au BufLeave *_test.go let g:neomake_go_enabled_makers = ['go', 'golint', 'govet']

autocmd! BufWritePost *.go Neomake