Fix #1930 - Finish ale_fix_on_save_ignore

* Implementation had a bug
* Documentation added
* Tests added

3 files changed, 156 insertions, 6 deletions

diff --git a/autoload/ale/fix.vim b/autoload/ale/fix.vim
index f5a3c0c2..92ae3e14 100644
--- a/autoload/ale/fix.vim
+++ b/autoload/ale/fix.vim
@@ -270,13 +270,13 @@ endfunction
 function! s:IgnoreFixers(callback_list, filetype, config) abort
     if type(a:config) is v:t_list
         let l:ignore_list = a:config
-    endif
-
-    let l:ignore_list = []
+    else
+        let l:ignore_list = []
 
-    for l:part in split(a:filetype , '\.')
-        call extend(l:ignore_list, get(a:config, l:part, []))
-    endfor
+        for l:part in split(a:filetype , '\.')
+            call extend(l:ignore_list, get(a:config, l:part, []))
+        endfor
+    endif
 
     call filter(a:callback_list, 'index(l:ignore_list, v:val) < 0')
 endfunction
diff --git a/doc/ale.txt b/doc/ale.txt
index 9971d355..3b194cb0 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -309,6 +309,9 @@ by default.
 
 |g:ale_fix_on_save| - Fix files when they are saved.
 
+Fixers can be disabled on save with |g:ale_fix_on_save_ignore|. They will
+still be run when you manually run |ALEFix|.
+
 
 ===============================================================================
 5. Language Server Protocol Support                                   *ale-lsp*
@@ -770,6 +773,43 @@ b:ale_fix_on_save                                           *b:ale_fix_on_save*
   Fixing files can be disabled or enabled for individual buffers by setting
   `b:ale_fix_on_save` to `0` or `1`.
 
+  Some fixers can be excluded from being run automatically when you save files
+  with the |g:ale_fix_on_save_ignore| setting.
+
+
+g:ale_fix_on_save_ignore                             *g:ale_fix_on_save_ignore*
+b:ale_fix_on_save_ignore                             *b:ale_fix_on_save_ignore*
+
+  Type: |Dictionary| or |List|
+  Default: `{}`
+
+  Given a |Dictionary| mapping filetypes to |Lists| of fixers to ignore, or
+  just a |List| of fixers to ignore, exclude those fixers from being run
+  automatically when files are saved.
+
+  You can disable some fixers in your ftplugin file: >
+
+  " Disable fixers 'b' and 'c' when fixing on safe for this buffer.
+  let b:ale_fix_on_save_ignore = ['b', 'c']
+  " Alternatively, define ignore lists for different filetypes.
+  let b:ale_fix_on_save_ignore = {'foo': ['b'], 'bar': ['c']}
+<
+  You can disable some fixers globally per filetype like so: >
+
+  let g:ale_fixers = {'foo': ['a', 'b'], 'bar': ['c', 'd']}
+  let g:ale_fix_on_save = 1
+  " For filetype `foo.bar`, only fixers 'b' and 'd' will be run on save.
+  let g:ale_fix_on_save_ignore = {'foo': ['a'], 'bar': ['c']}
+  " Alternatively, disable these fixers on save for all filetypes.
+  let g:ale_fix_on_save_ignore = ['a', 'c']
+<
+  You can ignore fixers based on matching |Funcref| values too: >
+
+  let g:AddBar = {buffer, lines -> lines + ['bar']}
+  let g:ale_fixers = {'foo': g:AddBar}
+  " The lambda fixer will be ignored, as it will be found in the ignore list.
+  let g:ale_fix_on_save_ignore = [g:AddBar]
+<
 
 g:ale_history_enabled                                   *g:ale_history_enabled*
 
diff --git a/test/fix/test_ale_fix_ignore.vader b/test/fix/test_ale_fix_ignore.vader
new file mode 100644
index 00000000..5eb9b9ab
--- /dev/null
+++ b/test/fix/test_ale_fix_ignore.vader
@@ -0,0 +1,110 @@
+Before:
+  Save g:ale_fixers
+  Save g:ale_fix_on_save
+  Save g:ale_fix_on_save_ignore
+
+  let g:ale_fix_on_save = 1
+  let g:ale_fixers = {'abc': ['a', 'b'], 'xyz': ['c', 'd']}
+  unlet! b:ale_fixers
+  unlet! b:ale_fix_on_save_ignore
+
+  function FixerA(buffer, lines) abort
+    return a:lines + ['a']
+  endfunction
+
+  function FixerB(buffer, lines) abort
+    return a:lines + ['b']
+  endfunction
+
+  function FixerC(buffer, lines) abort
+    return a:lines + ['c']
+  endfunction
+
+  function FixerD(buffer, lines) abort
+    return a:lines + ['d']
+  endfunction
+
+  set filetype=abc.xyz
+  let g:test_filename = tempname()
+  execute 'noautocmd silent file ' . fnameescape(g:test_filename)
+
+  call ale#fix#registry#Add('a', 'FixerA', ['abc'], '')
+  call ale#fix#registry#Add('b', 'FixerB', ['abc'], '')
+  call ale#fix#registry#Add('c', 'FixerC', ['xyz'], '')
+  call ale#fix#registry#Add('d', 'FixerD', ['xyz'], '')
+
+After:
+  Restore
+
+  if exists('g:test_filename') && filereadable(g:test_filename)
+    call delete(g:test_filename)
+  endif
+
+  unlet! b:ale_fixers
+  unlet! b:ale_fix_on_save_ignore
+  unlet! g:test_filename
+
+  delfunction FixerA
+  delfunction FixerB
+  delfunction FixerC
+  delfunction FixerD
+
+  call ale#fix#registry#ResetToDefaults()
+
+Given abc.xyz (An empty file):
+Execute(Ignoring with a filetype in a global Dictionary should work):
+  let g:ale_fix_on_save_ignore = {'abc': ['b'], 'xyz': ['c']}
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'd'], getline(1, '$')
+
+Execute(Ignoring with a filetype in a global List should work):
+  let g:ale_fix_on_save_ignore = ['b', 'c']
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'd'], getline(1, '$')
+
+Execute(Ignoring with a filetype in a local Dictionary should work):
+  let g:ale_fix_on_save_ignore = {'abc': ['b'], 'xyz': ['c']}
+  " The local Dictionary should entirely replace the global one.
+  let b:ale_fix_on_save_ignore = {'abc': ['b']}
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'c', 'd'], getline(1, '$')
+
+Execute(Ignoring with a filetype in a local List should work):
+  let g:ale_fix_on_save_ignore = {'abc': ['b'], 'xyz': ['c']}
+  " The local List should entirely replace the global Dictionary.
+  let b:ale_fix_on_save_ignore = ['b']
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'c', 'd'], getline(1, '$')
+
+Execute(Ignoring functions by reference with a Dictionary should work):
+  let g:ale_fixers = {
+  \ 'abc': [function('FixerA'), function('FixerB')],
+  \ 'xyz': [function('FixerC'), function('FixerD')],
+  \}
+  let b:ale_fix_on_save_ignore = {
+  \ 'abc': [function('FixerB')],
+  \ 'xyz': [function('FixerC')],
+  \}
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'd'], getline(1, '$')
+
+Execute(Ignoring functions by reference with a List should work):
+  let g:ale_fixers = {
+  \ 'abc': [function('FixerA'), function('FixerB')],
+  \ 'xyz': [function('FixerC'), function('FixerD')],
+  \}
+  let b:ale_fix_on_save_ignore = [function('FixerB'), function('FixerC')]
+
+  call ale#events#SaveEvent(bufnr(''))
+
+  AssertEqual ['', 'a', 'd'], getline(1, '$')