rubocop checker for syntastic.vim.

rubocop.vim

"============================================================================
"File:        rubocop.vim
"Description: rubocop checker for syntastic.vim
"Author:      mybeky  <mybeky at gmail.com>
"
"============================================================================
if exists("g:loaded_syntastic_ruby_robocop_checker")
    finish
endif
let g:loaded_syntastic_ruby_robocop_checker=1

function! SyntaxCheckers_ruby_rubocop_IsAvailable()
    return executable('rubocop')
endfunction

function! SyntaxCheckers_ruby_rubocop_GetLocList()
    let makeprg = syntastic#makeprg#build({
                \ 'exe': 'rubocop',
                \ 'args': ' -e -s' })
    let errorformat = '%f:%l: %t: %m'

    let loclist=SyntasticMake({ 'makeprg': makeprg, 'errorformat': errorformat })

    let n = len(loclist) - 1
    while n >= 0
        let loclist[n]['type'] = loclist[n]['type'] == 'C' ? 'W' : 'E'
        let n -= 1
    endwhile

    return sort(loclist, 's:CmpLoclist')
endfunction

function! s:CmpLoclist(a, b)
    return a:a['lnum'] - a:b['lnum']
endfunction

call g:SyntasticRegistry.CreateAndRegisterChecker({
    \ 'filetype': 'ruby',
    \ 'name': 'rubocop' })

add let g:syntastic_ruby_checkers=['rubocop'] to your .vimrc

Someone has contributed a RuboCop checker upstream last week vim-syntastic/syntastic@02dbc64