Add option to open loclist/quicklist when there are errors (#266)

* Add option to open loclist/quicklist when there are errors

I copied PR #137, and tries to complete it by correcting some issues and
adding vader tests.

About tests, first time with vader, can you give some feedback if there
are what you expected in PR #137.

* Remove old code + fix indent issue

* add g:ale_keep_list_window_open option

* Correct bug with keep open option

* Add comment into vader file

* Fix errors for Travis CI build

autoload/ale/engine.vim

@@ -161,8 +161,8 @@ function! s:HandleExit(job) abort
     let g:ale_buffer_info[l:buffer].loclist = g:ale_buffer_info[l:buffer].new_loclist
     let g:ale_buffer_info[l:buffer].new_loclist = []
 
-    if g:ale_set_loclist
-        call setloclist(0, g:ale_buffer_info[l:buffer].loclist)
+    if g:ale_set_quickfix || g:ale_set_loclist
+        call ale#list#SetLists(g:ale_buffer_info[l:buffer].loclist)
     endif
 
     if g:ale_set_signs

autoload/ale/list.vim

@@ -0,0 +1,49 @@
+" Author: Bjorn Neergaard <bjorn@neersighted.com>, modified by Yann fery <yann@fery.me>
+" Description: Manages the loclist and quickfix lists
+
+" Return 1 if there is a buffer with buftype == 'quickfix' in bufffer list
+function! ale#list#IsQuickfixOpen() abort
+    for l:buf in range(1, bufnr('$'))
+        if getbufvar(l:buf, '&buftype') ==# 'quickfix' 
+            return 1
+        endif
+    endfor
+    return 0 
+endfunction
+
+function! ale#list#SetLists(loclist) abort
+    if g:ale_set_quickfix
+        call setqflist(a:loclist)
+    elseif g:ale_set_loclist
+        call setloclist(0, a:loclist)
+    endif
+
+    " If we don't auto-open lists, bail out here.
+    if !g:ale_open_list && !g:ale_keep_list_window_open
+        return
+    endif
+
+    " If we have errors in our list, open the list. Only if it isn't already open
+    if len(a:loclist) > 0 || g:ale_keep_list_window_open
+        let l:winnr = winnr()
+
+        if g:ale_set_quickfix
+            copen
+        elseif g:ale_set_loclist
+            lopen
+        endif
+
+        " If focus changed, restore it (jump to the last window).
+        if l:winnr !=# winnr()
+            wincmd p
+        endif
+
+        " Only close if the list is totally empty (relying on Vim's state, not our
+        " own). This keeps us from closing the window when other plugins have
+        " populated it.
+    elseif !g:ale_keep_list_window_open && g:ale_set_quickfix && len(getqflist()) == 0
+        cclose
+    elseif !g:ale_keep_list_window_open && len(getloclist(0)) == 0
+        lclose
+    endif
+endfunction