Use a new window for the ALEFixSuggest command, and document it better

autoload/ale/fix/registry.vim

@@ -116,44 +116,56 @@ endfunction
 " Suggest functions to use from the registry.
 function! ale#fix#registry#Suggest(filetype) abort
     let l:type_list = split(a:filetype, '\.')
-    let l:first_for_filetype = 1
+    let l:filetype_fixer_list = []
-    let l:first_generic = 1
 
     for l:key in sort(keys(s:entries))
         let l:suggested_filetypes = s:entries[l:key].suggested_filetypes
 
         if s:ShouldSuggestForType(l:suggested_filetypes, l:type_list)
-            if l:first_for_filetype
+            call add(
-                let l:first_for_filetype = 0
+            \   l:filetype_fixer_list,
-                echom 'Try the following fixers appropriate for the filetype:'
+            \   printf('%s - %s', string(l:key), s:entries[l:key].description),
-                echom ''
+            \)
-            endif
-
-            echom printf('%s - %s', string(l:key), s:entries[l:key].description)
         endif
     endfor
 
+    let l:generic_fixer_list = []
 
     for l:key in sort(keys(s:entries))
         if empty(s:entries[l:key].suggested_filetypes)
-            if l:first_generic
+            call add(
-                if !l:first_for_filetype
+            \   l:generic_fixer_list,
-                    echom ''
+            \   printf('%s - %s', string(l:key), s:entries[l:key].description),
-                endif
+            \)
-
-                let l:first_generic = 0
-                echom 'Try the following generic fixers:'
-                echom ''
-            endif
-
-            echom printf('%s - %s', string(l:key), s:entries[l:key].description)
         endif
     endfor
 
-    if l:first_for_filetype && l:first_generic
+    let l:filetype_fixer_header = !empty(l:filetype_fixer_list)
-        echom 'There is nothing in the registry to suggest.'
+    \   ? ['Try the following fixers appropriate for the filetype:', '']
+    \   : []
+    let l:generic_fixer_header = !empty(l:generic_fixer_list)
+    \   ? ['Try the following generic fixers:', '']
+    \   : []
+
+    let l:has_both_lists = !empty(l:filetype_fixer_list) && !empty(l:generic_fixer_list)
+
+    let l:lines =
+    \   l:filetype_fixer_header
+    \   + l:filetype_fixer_list
+    \   + (l:has_both_lists ? [''] : [])
+    \   + l:generic_fixer_header
+    \   + l:generic_fixer_list
+
+    if empty(l:lines)
+        let l:lines = ['There is nothing in the registry to suggest.']
     else
-        echom ''
+        let l:lines += ['', 'See :help ale-fix-configuration']
-        echom 'See :help ale-fix-configuration'
     endif
+
+    let l:lines += ['', 'Press q to close this window']
+
+    new +set\ filetype=ale-fix-suggest
+    call setline(1, l:lines)
+    setlocal nomodified
+    setlocal nomodifiable
 endfunction

doc/ale.txt

@@ -131,7 +131,9 @@ ALE supports the following key features for linting:
 7. Setting syntax highlights for errors.
 
 ALE can fix problems with files with the |ALEFix| command, using the same job
-control functionality used for checking for problems.
+control functionality used for checking for problems. Try using the
+|ALEFixSuggest| command for browsing tools that can be used to fix problems
+for the current buffer.
 
 ===============================================================================
 2. Supported Languages & Tools                                    *ale-support*
@@ -915,6 +917,9 @@ run, the variable |g:ale_fixers| will be read for getting a |List| of commands
 for filetypes, split on `.`, and the functions named in |g:ale_fixers| will be
 executed for fixing the errors.
 
+The |ALEFixSuggest| command can be used to suggest tools that be used to
+fix problems for the current buffer.
+
 The values for `g:ale_fixers` can be a list of |String|, |Funcref|, or
 |lambda| values. String values must either name a function, or a short name
 for a function set in the ALE fixer registry.
@@ -1019,6 +1024,13 @@ ALEFix                                                                 *ALEFix*
   A plug mapping `<Plug>(ale_fix)` is defined for this command.
 
 
+ALEFixSuggest                                                   *ALEFixSuggest*
+
+  Suggest tools that can be used to fix problems in the current buffer.
+
+  See |ale-fix| for more information.
+
+
 ALELint                                                               *ALELint*
 
   Run ALE once for the current buffer. This command can be used to run ALE

ftplugin/ale-fix-suggest.vim

@@ -0,0 +1,2 @@
+" Close the ALEFixSuggest window with the q key.
+noremap <buffer> q :q!<CR>

syntax/ale-fix-suggest.vim

@@ -0,0 +1,13 @@
+if exists('b:current_syntax')
+    finish
+endif
+
+syn match aleFixerComment /^.*$/
+syn match aleFixerName /^'[^']*'/
+syn match aleFixerHelp /^See :help ale-fix-configuration/
+
+hi def link aleFixerComment Comment
+hi def link aleFixerName String
+hi def link aleFixerHelp Statement
+
+let b:current_syntax = 'ale-fix-suggest'

test/test_ale_fix_suggest.vader

@@ -1,15 +1,27 @@
 Before:
   call ale#fix#registry#Clear()
 
-  function GetSuggestions()
+  let g:buffer = bufnr('')
-    redir => l:output
-      silent ALEFixSuggest
-    redir END
 
-    return split(l:output, "\n")
+  function GetSuggestions()
+    silent ALEFixSuggest
+
+    if bufnr('') != g:buffer
+      let l:lines = getline(1, '$')
+    else
+      let l:lines = []
+    endif
+
+    return l:lines
   endfunction
 
 After:
+  if bufnr('') != g:buffer
+    :q!
+  endif
+
+  unlet! g:buffer
+
   call ale#fix#registry#ResetToDefaults()
   delfunction GetSuggestions
 
@@ -17,9 +29,18 @@ Execute(ALEFixSuggest should return something sensible with no suggestions):
   AssertEqual
   \ [
   \   'There is nothing in the registry to suggest.',
+  \   '',
+  \   'Press q to close this window',
   \ ],
   \ GetSuggestions()
 
+Execute(ALEFixSuggest should set the appropriate settings):
+  silent ALEFixSuggest
+
+  AssertEqual 'ale-fix-suggest', &filetype
+  Assert !&modified, 'The buffer was marked as modified'
+  Assert !&modifiable, 'The buffer was modifiable'
+
 Execute(ALEFixSuggest output should be correct for only generic handlers):
   call ale#fix#registry#Add('zed', 'XYZ', [], 'Zedify things.')
   call ale#fix#registry#Add('alpha', 'XYZ', [], 'Alpha things.')
@@ -32,6 +53,8 @@ Execute(ALEFixSuggest output should be correct for only generic handlers):
   \   '''zed'' - Zedify things.',
   \   '',
   \   'See :help ale-fix-configuration',
+  \   '',
+  \   'Press q to close this window',
   \ ],
   \ GetSuggestions()
 
@@ -49,6 +72,8 @@ Execute(ALEFixSuggest output should be correct for only filetype handlers):
   \   '''zed'' - Zedify things.',
   \   '',
   \   'See :help ale-fix-configuration',
+  \   '',
+  \   'Press q to close this window',
   \ ],
   \ GetSuggestions()
 
@@ -71,5 +96,7 @@ Execute(ALEFixSuggest should suggest filetype and generic handlers):
   \   '''generic'' - Generic things.',
   \   '',
   \   'See :help ale-fix-configuration',
+  \   '',
+  \   'Press q to close this window',
   \ ],
   \ GetSuggestions()