vimrc

nnoremap <leader>ls :OpenSpecInSplit<cr>

fun! OpenFilesInSplit(left, right)
  if a:left == a:right
    return
  endif

  only
  exec "edit " . a:left
  exec "vs " . a:right
  execute "normal! \<c-w>t"
endfun

fun! OpenSpecInSplit()
  let file = expand('%:p')

  if match(file, "app/") >= 0
    if match(file, "assets/javascripts") >= 0
      let f1 = substitute(file, "\\.js\.coffee", ".spec.coffee", "")
      let f2 = substitute(f1, "app\/assets\/javascripts\\/", "spec/javascripts/spec/", "")
    else
      let f1 = substitute(file, "\\.rb", "_spec.rb", "")
      let f2 = substitute(f1, "app\\/", "spec/", "")
    endif
    call OpenFilesInSplit(f2, file)
    exec "w"
  else
    if match(file, "spec/") >= 0
      if match(file, "spec/javascripts") >= 0
        let f1 = substitute(file, "\.spec\.coffee", ".js.coffee", "")
        let f2 = substitute(f1, "spec/javascripts/spec", "app/assets/javascripts", "")
      else
        let f1 = substitute(file, "\_spec", "", "")
        let f2 = substitute(f1, "spec/", "app/", "")
      endif
      call OpenFilesInSplit(file, f2)
      exec "w"
    endif
  endif
endfun
com! OpenSpecInSplit :call OpenSpecInSplit()