vim-patch:8.2.4482: no fuzzy cmdline completion for user defined completion

Problem:    No fuzzy cmdline completion for user defined completion.
Solution:   Add fuzzy completion for user defined completion. (Yegappan
            Lakshmanan, closes vim/vim#9858)

https://github.com/vim/vim/commit/afd4ae35d66b2e7732eceb5ad9f6b4ece6b7c64c

Cherry-pick related docs from Vim runtime.

N/A patches for version.c:

vim-patch:8.2.4485: compiler warning for uninitialized variable
vim-patch:8.2.4732: duplicate code to free fuzzy matches

Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>

2 files changed, 302 insertions, 139 deletions

diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 4559e83e20..0d291881ba 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -111,12 +111,12 @@ static bool cmdline_fuzzy_completion_supported(const expand_T *const xp)
          && xp->xp_context != EXPAND_SHELLCMD
          && xp->xp_context != EXPAND_TAGS
          && xp->xp_context != EXPAND_TAGS_LISTFILES
-         && xp->xp_context != EXPAND_USER_DEFINED
          && xp->xp_context != EXPAND_USER_LIST;
 }
 
 /// Returns true if fuzzy completion for cmdline completion is enabled and
-/// "fuzzystr" is not empty.
+/// "fuzzystr" is not empty.  If search pattern is empty, then don't use fuzzy
+/// matching.
 bool cmdline_fuzzy_complete(const char *const fuzzystr)
   FUNC_ATTR_WARN_UNUSED_RESULT FUNC_ATTR_NONNULL_ALL FUNC_ATTR_PURE
 {
@@ -2585,16 +2585,10 @@ static int ExpandOther(char *pat, expand_T *xp, regmatch_T *rmp, char ***matches
   // right function to do the expansion.
   for (int i = 0; i < (int)ARRAY_SIZE(tab); i++) {
     if (xp->xp_context == tab[i].context) {
-      // Use fuzzy matching if 'wildoptions' has "fuzzy".
-      // If no search pattern is supplied, then don't use fuzzy
-      // matching and return all the found items.
-      const bool fuzzy = cmdline_fuzzy_complete(pat);
-
       if (tab[i].ic) {
         rmp->rm_ic = true;
       }
-      ExpandGeneric(xp, rmp, matches, numMatches, tab[i].func, tab[i].escaped,
-                    fuzzy ? pat : NULL);
+      ExpandGeneric(pat, xp, rmp, matches, numMatches, tab[i].func, tab[i].escaped);
       ret = OK;
       break;
     }
@@ -2735,7 +2729,7 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
   } else if (xp->xp_context == EXPAND_MAPPINGS) {
     ret = ExpandMappings(pat, &regmatch, numMatches, matches);
   } else if (xp->xp_context == EXPAND_USER_DEFINED) {
-    ret = ExpandUserDefined(xp, &regmatch, matches, numMatches);
+    ret = ExpandUserDefined(pat, xp, &regmatch, matches, numMatches);
   } else {
     ret = ExpandOther(pat, xp, &regmatch, matches, numMatches);
   }
@@ -2754,17 +2748,16 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
 /// obtain strings, one by one.  The strings are matched against a regexp
 /// program.  Matching strings are copied into an array, which is returned.
 ///
-/// If "fuzzystr" is not NULL, then fuzzy matching is used. Otherwise,
-/// regex matching is used.
-///
 /// @param func  returns a string from the list
-static void ExpandGeneric(expand_T *xp, regmatch_T *regmatch, char ***matches, int *numMatches,
-                          CompleteListItemGetter func, int escaped, const char *const fuzzystr)
+static void ExpandGeneric(const char *const pat, expand_T *xp, regmatch_T *regmatch,
+                          char ***matches, int *numMatches, CompleteListItemGetter func,
+                          int escaped)
 {
   int i;
   size_t count = 0;
   char *str;
-  const bool fuzzy = fuzzystr != NULL;
+
+  const bool fuzzy = cmdline_fuzzy_complete(pat);
 
   // count the number of matching names
   for (i = 0;; i++) {
@@ -2780,7 +2773,7 @@ static void ExpandGeneric(expand_T *xp, regmatch_T *regmatch, char ***matches, i
     if (!fuzzy) {
       match = vim_regexec(regmatch, str, (colnr_T)0);
     } else {
-      match = fuzzy_match_str(str, fuzzystr) != 0;
+      match = fuzzy_match_str(str, pat) != 0;
     }
     if (match) {
       count++;
@@ -2814,9 +2807,10 @@ static void ExpandGeneric(expand_T *xp, regmatch_T *regmatch, char ***matches, i
     if (!fuzzy) {
       match = vim_regexec(regmatch, str, (colnr_T)0);
     } else {
-      score = fuzzy_match_str(str, fuzzystr);
+      score = fuzzy_match_str(str, pat);
       match = (score != 0);
     }
+
     if (!match) {
       continue;
     }
@@ -3044,12 +3038,16 @@ static void *call_user_expand_func(user_expand_func_T user_expand_func, expand_T
   return ret;
 }
 
-/// Expand names with a function defined by the user.
-static int ExpandUserDefined(expand_T *xp, regmatch_T *regmatch, char ***matches, int *numMatches)
+/// Expand names with a function defined by the user (EXPAND_USER_DEFINED and
+/// EXPAND_USER_LIST).
+static int ExpandUserDefined(const char *const pat, expand_T *xp, regmatch_T *regmatch,
+                             char ***matches, int *numMatches)
 {
   char *e;
   garray_T ga;
 
+  const bool fuzzy = cmdline_fuzzy_complete(pat);
+
   *matches = NULL;
   *numMatches = 0;
   char *const retstr = call_user_expand_func((user_expand_func_T)call_func_retstr, xp);
@@ -3058,7 +3056,13 @@ static int ExpandUserDefined(expand_T *xp, regmatch_T *regmatch, char ***matches
     return FAIL;
   }
 
-  ga_init(&ga, (int)sizeof(char *), 3);
+  if (!fuzzy) {
+    ga_init(&ga, (int)sizeof(char *), 3);
+  } else {
+    ga_init(&ga, (int)sizeof(fuzmatch_str_T), 3);
+  }
+
+  int count = 0;
   for (char *s = retstr; *s != NUL; s = e) {
     e = vim_strchr(s, '\n');
     if (e == NULL) {
@@ -3067,10 +3071,32 @@ static int ExpandUserDefined(expand_T *xp, regmatch_T *regmatch, char ***matches
     const char keep = *e;
     *e = NUL;
 
-    const bool skip = xp->xp_pattern[0] && vim_regexec(regmatch, s, (colnr_T)0) == 0;
+    bool match;
+    int score = 0;
+    if (xp->xp_pattern[0] || fuzzy) {
+      if (!fuzzy) {
+        match = vim_regexec(regmatch, s, (colnr_T)0);
+      } else {
+        score = fuzzy_match_str(s, pat);
+        match = (score != 0);
+      }
+    } else {
+      match = true;               // match everything
+    }
+
     *e = keep;
-    if (!skip) {
-      GA_APPEND(char *, &ga, xstrnsave(s, (size_t)(e - s)));
+
+    if (match) {
+      if (!fuzzy) {
+        GA_APPEND(char *, &ga, xstrnsave(s, (size_t)(e - s)));
+      } else {
+        GA_APPEND(fuzmatch_str_T, &ga, ((fuzmatch_str_T){
+          .idx = count,
+          .str = xstrnsave(s, (size_t)(e - s)),
+          .score = score,
+        }));
+      }
+      count++;
     }
 
     if (*e != NUL) {
@@ -3078,8 +3104,14 @@ static int ExpandUserDefined(expand_T *xp, regmatch_T *regmatch, char ***matches
     }
   }
   xfree(retstr);
-  *matches = ga.ga_data;
-  *numMatches = ga.ga_len;
+
+  if (!fuzzy) {
+    *matches = ga.ga_data;
+    *numMatches = ga.ga_len;
+  } else {
+    fuzzymatches_to_strmatches(ga.ga_data, matches, count, false);
+    *numMatches = count;
+  }
   return OK;
 }
 
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index f5c84e0729..20e8214692 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -2670,9 +2670,8 @@ func Test_cmdline_complete_dlist()
   call assert_equal("\"dlist 10 /pat/ | chistory", @:)
 endfunc
 
-" Test for 'fuzzy' in 'wildoptions' (fuzzy completion)
-func Test_wildoptions_fuzzy()
-  " argument list (only for :argdel)
+" argument list (only for :argdel) fuzzy completion
+func Test_fuzzy_completion_arglist()
   argadd change.py count.py charge.py
   set wildoptions&
   call feedkeys(":argdel cge\<C-A>\<C-B>\"\<CR>", 'tx')
@@ -2681,8 +2680,11 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":argdel cge\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"argdel change.py charge.py', @:)
   %argdelete
+  set wildoptions&
+endfunc
 
-  " autocmd group name fuzzy completion
+" autocmd group name fuzzy completion
+func Test_fuzzy_completion_autocmd()
   set wildoptions&
   augroup MyFuzzyGroup
   augroup END
@@ -2696,8 +2698,11 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":augroup My*p\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"augroup My*p', @:)
   augroup! MyFuzzyGroup
+  set wildoptions&
+endfunc
 
-  " buffer name fuzzy completion
+" buffer name fuzzy completion
+func Test_fuzzy_completion_bufname()
   set wildoptions&
   edit SomeFile.txt
   enew
@@ -2711,24 +2716,29 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":b S*File.txt\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"b S*File.txt', @:)
   %bw!
+  set wildoptions&
+endfunc
 
-  " buffer name (full path) fuzzy completion
-  if has('unix')
-    set wildoptions&
-    call mkdir('Xcmd/Xstate/Xfile.js', 'p')
-    edit Xcmd/Xstate/Xfile.js
-    cd Xcmd/Xstate
-    enew
-    call feedkeys(":b CmdStateFile\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"b CmdStateFile', @:)
-    set wildoptions=fuzzy
-    call feedkeys(":b CmdStateFile\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_match('Xcmd/Xstate/Xfile.js$', @:)
-    cd -
-    call delete('Xcmd', 'rf')
-  endif
+" buffer name (full path) fuzzy completion
+func Test_fuzzy_completion_bufname_fullpath()
+  CheckUnix
+  set wildoptions&
+  call mkdir('Xcmd/Xstate/Xfile.js', 'p')
+  edit Xcmd/Xstate/Xfile.js
+  cd Xcmd/Xstate
+  enew
+  call feedkeys(":b CmdStateFile\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"b CmdStateFile', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":b CmdStateFile\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_match('Xcmd/Xstate/Xfile.js$', @:)
+  cd -
+  call delete('Xcmd', 'rf')
+  set wildoptions&
+endfunc
 
-  " :behave suboptions fuzzy completion
+" :behave suboptions fuzzy completion
+func Test_fuzzy_completion_behave()
   set wildoptions&
   call feedkeys(":behave xm\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"behave xm', @:)
@@ -2743,10 +2753,15 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":behave win\<C-D>\<F4>\<C-B>\"\<CR>", 'tx')
   call assert_equal('mswin', g:Sline)
   call assert_equal('"behave win', @:)
+  set wildoptions&
+endfunc
 
-  " colorscheme name fuzzy completion - NOT supported
+" " colorscheme name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_colorscheme()
+" endfunc
 
-  " built-in command name fuzzy completion
+" built-in command name fuzzy completion
+func Test_fuzzy_completion_cmdname()
   set wildoptions&
   call feedkeys(":sbwin\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"sbwin', @:)
@@ -2757,24 +2772,31 @@ func Test_wildoptions_fuzzy()
   call assert_equal('"sbrewind', @:)
   call feedkeys(":sbr*d\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"sbr*d', @:)
+  set wildoptions&
+endfunc
 
-  " compiler name fuzzy completion - NOT supported
+" " compiler name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_compiler()
+" endfunc
 
-  " :cscope suboptions fuzzy completion
-  if has('cscope')
-    set wildoptions&
-    call feedkeys(":cscope ret\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"cscope ret', @:)
-    call feedkeys(":cscope re*t\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"cscope reset', @:)
-    set wildoptions=fuzzy
-    call feedkeys(":cscope ret\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"cscope reset', @:)
-    call feedkeys(":cscope re*t\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"cscope re*t', @:)
-  endif
+" :cscope suboptions fuzzy completion
+func Test_fuzzy_completion_cscope()
+  CheckFeature cscope
+  set wildoptions&
+  call feedkeys(":cscope ret\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"cscope ret', @:)
+  call feedkeys(":cscope re*t\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"cscope reset', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":cscope ret\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"cscope reset', @:)
+  call feedkeys(":cscope re*t\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"cscope re*t', @:)
+  set wildoptions&
+endfunc
 
-  " :diffget/:diffput buffer name fuzzy completion
+" :diffget/:diffput buffer name fuzzy completion
+func Test_fuzzy_completion_diff()
   new SomeBuffer
   diffthis
   new OtherBuffer
@@ -2790,26 +2812,37 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":diffput sbuf\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"diffput SomeBuffer', @:)
   %bw!
+  set wildoptions&
+endfunc
 
-  " directory name fuzzy completion - NOT supported
+" " directory name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_dirname()
+" endfunc
 
-  " environment variable name fuzzy completion
+" environment variable name fuzzy completion
+func Test_fuzzy_completion_env()
   set wildoptions&
   call feedkeys(":echo $VUT\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"echo $VUT', @:)
   set wildoptions=fuzzy
   call feedkeys(":echo $VUT\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"echo $VIMRUNTIME', @:)
+  set wildoptions&
+endfunc
 
-  " autocmd event fuzzy completion
+" autocmd event fuzzy completion
+func Test_fuzzy_completion_autocmd_event()
   set wildoptions&
   call feedkeys(":autocmd BWout\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"autocmd BWout', @:)
   set wildoptions=fuzzy
   call feedkeys(":autocmd BWout\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"autocmd BufWipeout', @:)
+  set wildoptions&
+endfunc
 
-  " vim expression fuzzy completion
+" vim expression fuzzy completion
+func Test_fuzzy_completion_expr()
   let g:PerPlaceCount = 10
   set wildoptions&
   call feedkeys(":let c = ppc\<Tab>\<C-B>\"\<CR>", 'tx')
@@ -2817,32 +2850,49 @@ func Test_wildoptions_fuzzy()
   set wildoptions=fuzzy
   call feedkeys(":let c = ppc\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"let c = PerPlaceCount', @:)
+  set wildoptions&
+endfunc
 
-  " file name fuzzy completion - NOT supported
+" " file name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_filename()
+" endfunc
 
-  " files in path fuzzy completion - NOT supported
+" " files in path fuzzy completion - NOT supported
+" func Test_fuzzy_completion_filesinpath()
+" endfunc
 
-  " filetype name fuzzy completion - NOT supported
+" " filetype name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_filetype()
+" endfunc
 
-  " user defined function name completion
+" user defined function name completion
+func Test_fuzzy_completion_userdefined_func()
   set wildoptions&
-  call feedkeys(":call Test_w_fuz\<Tab>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"call Test_w_fuz', @:)
+  call feedkeys(":call Test_f_u_f\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"call Test_f_u_f', @:)
   set wildoptions=fuzzy
-  call feedkeys(":call Test_w_fuz\<Tab>\<C-B>\"\<CR>", 'tx')
-  call assert_equal('"call Test_wildoptions_fuzzy()', @:)
+  call feedkeys(":call Test_f_u_f\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"call Test_fuzzy_completion_userdefined_func()', @:)
+  set wildoptions&
+endfunc
 
-  " user defined command name completion
+" user defined command name completion
+func Test_fuzzy_completion_userdefined_cmd()
   set wildoptions&
   call feedkeys(":MsFeat\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"MsFeat', @:)
   set wildoptions=fuzzy
   call feedkeys(":MsFeat\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"MissingFeature', @:)
+  set wildoptions&
+endfunc
 
-  " :help tag fuzzy completion - NOT supported
+" " :help tag fuzzy completion - NOT supported
+" func Test_fuzzy_completion_helptag()
+" endfunc
 
-  " highlight group name fuzzy completion
+" highlight group name fuzzy completion
+func Test_fuzzy_completion_hlgroup()
   set wildoptions&
   call feedkeys(":highlight SKey\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"highlight SKey', @:)
@@ -2853,8 +2903,11 @@ func Test_wildoptions_fuzzy()
   call assert_equal('"highlight SpecialKey', @:)
   call feedkeys(":highlight Sp*Key\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"highlight Sp*Key', @:)
+  set wildoptions&
+endfunc
 
-  " :history suboptions fuzzy completion
+" :history suboptions fuzzy completion
+func Test_fuzzy_completion_history()
   set wildoptions&
   call feedkeys(":history dg\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"history dg', @:)
@@ -2865,26 +2918,34 @@ func Test_wildoptions_fuzzy()
   call assert_equal('"history debug', @:)
   call feedkeys(":history se*h\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"history se*h', @:)
+  set wildoptions&
+endfunc
 
-  " :language locale name fuzzy completion
-  if has('unix')
-    set wildoptions&
-    call feedkeys(":lang psx\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"lang psx', @:)
-    set wildoptions=fuzzy
-    call feedkeys(":lang psx\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"lang POSIX', @:)
-  endif
+" :language locale name fuzzy completion
+func Test_fuzzy_completion_lang()
+  CheckUnix
+  set wildoptions&
+  call feedkeys(":lang psx\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"lang psx', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":lang psx\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"lang POSIX', @:)
+  set wildoptions&
+endfunc
 
-  " :mapclear buffer argument fuzzy completion
+" :mapclear buffer argument fuzzy completion
+func Test_fuzzy_completion_mapclear()
   set wildoptions&
   call feedkeys(":mapclear buf\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"mapclear buf', @:)
   set wildoptions=fuzzy
   call feedkeys(":mapclear buf\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"mapclear <buffer>', @:)
+  set wildoptions&
+endfunc
 
-  " map name fuzzy completion
+" map name fuzzy completion
+func Test_fuzzy_completion_mapname()
   " test regex completion works
   set wildoptions=fuzzy
   call feedkeys(":cnoremap <ex\<Tab> <esc> \<Tab>\<C-B>\"\<CR>", 'tx')
@@ -2919,8 +2980,11 @@ func Test_wildoptions_fuzzy()
   nunmap <Plug>fendoff
   nunmap <Plug>state
   nunmap <Plug>FendingOff
+  set wildoptions&
+endfunc
 
-  " abbreviation fuzzy completion
+" abbreviation fuzzy completion
+func Test_fuzzy_completion_abbr()
   set wildoptions=fuzzy
   call feedkeys(":iabbr wait\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal("\"iabbr <nowait>", @:)
@@ -2930,26 +2994,34 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":iabbr a1z\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal("\"iabbr a1z\t", @:)
   iunabbrev WaitForCompletion
+  set wildoptions&
+endfunc
 
-  " menu name fuzzy completion
-  if has('gui_running')
-    set wildoptions&
-    call feedkeys(":menu pup\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"menu pup', @:)
-    set wildoptions=fuzzy
-    call feedkeys(":menu pup\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"menu PopUp.', @:)
-  endif
+" menu name fuzzy completion
+func Test_fuzzy_completion_menu()
+  CheckGui
+  set wildoptions&
+  call feedkeys(":menu pup\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"menu pup', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":menu pup\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"menu PopUp.', @:)
+  set wildoptions&
+endfunc
 
-  " :messages suboptions fuzzy completion
+" :messages suboptions fuzzy completion
+func Test_fuzzy_completion_messages()
   set wildoptions&
   call feedkeys(":messages clr\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"messages clr', @:)
   set wildoptions=fuzzy
   call feedkeys(":messages clr\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"messages clear', @:)
+  set wildoptions&
+endfunc
 
-  " :set option name fuzzy completion
+" :set option name fuzzy completion
+func Test_fuzzy_completion_option()
   set wildoptions&
   call feedkeys(":set brkopt\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"set brkopt', @:)
@@ -2962,67 +3034,94 @@ func Test_wildoptions_fuzzy()
   set wildoptions=fuzzy
   call feedkeys(":set fixeol\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"set fixendofline', @:)
+  set wildoptions&
+endfunc
 
-  " :set <term_option>
-  " Nvim does not support term options
-  " set wildoptions&
-  " call feedkeys(":set t_E\<Tab>\<C-B>\"\<CR>", 'tx')
-  " call assert_equal('"set t_EC', @:)
-  " call feedkeys(":set <t_E\<Tab>\<C-B>\"\<CR>", 'tx')
-  " call assert_equal('"set <t_EC>', @:)
-  " set wildoptions=fuzzy
-  " call feedkeys(":set t_E\<Tab>\<C-B>\"\<CR>", 'tx')
-  " call assert_equal('"set t_EC', @:)
-  " call feedkeys(":set <t_E\<Tab>\<C-B>\"\<CR>", 'tx')
-  " call assert_equal('"set <t_EC>', @:)
+" :set <term_option>
+func Test_fuzzy_completion_term_option()
+  throw 'Skipped: Nvim does not support term options'
+  set wildoptions&
+  call feedkeys(":set t_E\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set t_EC', @:)
+  call feedkeys(":set <t_E\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set <t_EC>', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":set t_E\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set t_EC', @:)
+  call feedkeys(":set <t_E\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"set <t_EC>', @:)
+  set wildoptions&
+endfunc
 
-  " :packadd directory name fuzzy completion - NOT supported
+" " :packadd directory name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_packadd()
+" endfunc
 
-  " shell command name fuzzy completion - NOT supported
+" " shell command name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_shellcmd()
+" endfunc
 
-  " :sign suboptions fuzzy completion
+" :sign suboptions fuzzy completion
+func Test_fuzzy_completion_sign()
   set wildoptions&
   call feedkeys(":sign ufe\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"sign ufe', @:)
   set wildoptions=fuzzy
   call feedkeys(":sign ufe\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"sign undefine', @:)
+  set wildoptions&
+endfunc
 
-  " :syntax suboptions fuzzy completion
+" :syntax suboptions fuzzy completion
+func Test_fuzzy_completion_syntax_cmd()
   set wildoptions&
   call feedkeys(":syntax kwd\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"syntax kwd', @:)
   set wildoptions=fuzzy
   call feedkeys(":syntax kwd\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"syntax keyword', @:)
+  set wildoptions&
+endfunc
 
-  " syntax group name fuzzy completion
+" syntax group name fuzzy completion
+func Test_fuzzy_completion_syntax_group()
   set wildoptions&
   call feedkeys(":syntax list mpar\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"syntax list mpar', @:)
   set wildoptions=fuzzy
   call feedkeys(":syntax list mpar\<Tab>\<C-B>\"\<CR>", 'tx')
-  " Fuzzy match favours NvimParenthesis over MatchParen
+  " Fuzzy match prefers NvimParenthesis over MatchParen
   " call assert_equal('"syntax list MatchParen', @:)
   call assert_equal('"syntax list NvimParenthesis', @:)
+  set wildoptions&
+endfunc
 
-  " :syntime suboptions fuzzy completion
-  if has('profile')
-    set wildoptions&
-    call feedkeys(":syntime clr\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"syntime clr', @:)
-    set wildoptions=fuzzy
-    call feedkeys(":syntime clr\<Tab>\<C-B>\"\<CR>", 'tx')
-    call assert_equal('"syntime clear', @:)
-  endif
+" :syntime suboptions fuzzy completion
+func Test_fuzzy_completion_syntime()
+  CheckFeature profile
+  set wildoptions&
+  call feedkeys(":syntime clr\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"syntime clr', @:)
+  set wildoptions=fuzzy
+  call feedkeys(":syntime clr\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal('"syntime clear', @:)
+  set wildoptions&
+endfunc
 
-  " tag name fuzzy completion - NOT supported
+" " tag name fuzzy completion - NOT supported
+" func Test_fuzzy_completion_tagname()
+" endfunc
 
-  " tag name and file fuzzy completion - NOT supported
+" " tag name and file fuzzy completion - NOT supported
+" func Test_fuzzy_completion_tagfile()
+" endfunc
 
-  " user names fuzzy completion - how to test this functionality?
+" " user names fuzzy completion - how to test this functionality?
+" func Test_fuzzy_completion_username()
+" endfunc
 
-  " user defined variable name fuzzy completion
+" user defined variable name fuzzy completion
+func Test_fuzzy_completion_userdefined_var()
   let g:SomeVariable=10
   set wildoptions&
   call feedkeys(":let SVar\<Tab>\<C-B>\"\<CR>", 'tx')
@@ -3030,8 +3129,11 @@ func Test_wildoptions_fuzzy()
   set wildoptions=fuzzy
   call feedkeys(":let SVar\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"let SomeVariable', @:)
+  set wildoptions&
+endfunc
 
-  " Test for sorting the results by the best match
+" Test for sorting the results by the best match
+func Test_fuzzy_completion_cmd_sort_results()
   %bw!
   command T123format :
   command T123goformat :
@@ -3049,9 +3151,11 @@ func Test_wildoptions_fuzzy()
   delcommand T123state
   delcommand T123FendingOff
   %bw
+  set wildoptions&
+endfunc
 
-  " Test for fuzzy completion of a command with lower case letters and a
-  " number
+" Test for fuzzy completion of a command with lower case letters and a number
+func Test_fuzzy_completion_cmd_alnum()
   command Foo2Bar :
   set wildoptions=fuzzy
   call feedkeys(":foo2\<Tab>\<C-B>\"\<CR>", 'tx')
@@ -3061,8 +3165,11 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":bar\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"Foo2Bar', @:)
   delcommand Foo2Bar
+  set wildoptions&
+endfunc
 
-  " Test for command completion for a command starting with 'k'
+" Test for command completion for a command starting with 'k'
+func Test_fuzzy_completion_cmd_k()
   command KillKillKill :
   set wildoptions&
   call feedkeys(":killkill\<Tab>\<C-B>\"\<CR>", 'tx')
@@ -3071,9 +3178,33 @@ func Test_wildoptions_fuzzy()
   call feedkeys(":killkill\<Tab>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"KillKillKill', @:)
   delcom KillKillKill
+  set wildoptions&
+endfunc
 
+" Test for fuzzy completion for user defined custom completion function
+func Test_fuzzy_completion_custom_func()
+  func Tcompl(a, c, p)
+    return "format\ngoformat\nTestFOrmat\nfendoff\nstate"
+  endfunc
+  command -nargs=* -complete=custom,Tcompl Fuzzy :
+  set wildoptions&
+  call feedkeys(":Fuzzy fo\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy format", @:)
+  call feedkeys(":Fuzzy xy\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy xy", @:)
+  call feedkeys(":Fuzzy ttt\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy ttt", @:)
+  set wildoptions=fuzzy
+  call feedkeys(":Fuzzy \<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy format goformat TestFOrmat fendoff state", @:)
+  call feedkeys(":Fuzzy fo\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy format TestFOrmat goformat fendoff", @:)
+  call feedkeys(":Fuzzy xy\<Tab>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy xy", @:)
+  call feedkeys(":Fuzzy ttt\<C-A>\<C-B>\"\<CR>", 'tx')
+  call assert_equal("\"Fuzzy TestFOrmat", @:)
+  delcom Fuzzy
   set wildoptions&
-  %bw!
 endfunc
 
 " Test for :breakadd argument completion