diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index c95a16cd25..d59618a075 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1263,6 +1263,56 @@ complete_info([{what}])                                        *complete_info()*
                 Return: ~
                   (`table`)
 
+complete_match([{lnum}, {col}])                               *complete_match()*
+		Searches backward from the given position and returns a List
+		of matches according to the 'isexpand' option. When no
+		arguments are provided, uses the current cursor position.
+
+		Each match is represented as a List containing
+		[startcol, trigger_text] where:
+		- startcol: column position where completion should start,
+		  or -1 if no trigger position is found. For multi-character
+		  triggers, returns the column of the first character.
+		- trigger_text: the matching trigger string from 'isexpand',
+		  or empty string if no match was found or when using the
+		  default 'iskeyword' pattern.
+
+		When 'isexpand' is empty, uses the 'iskeyword' pattern
+		"\k\+$" to find the start of the current keyword.
+
+		Examples: >vim
+		  set isexpand=.,->,/,/*,abc
+		  func CustomComplete()
+		    let res = complete_match()
+		    if res->len() == 0 | return | endif
+		    let [col, trigger] = res[0]
+		    let items = []
+		    if trigger == '/*'
+		      let items = ['/** */']
+		    elseif trigger == '/'
+		      let items = ['/*! */', '// TODO:', '// fixme:']
+		    elseif trigger == '.'
+		      let items = ['length()']
+		    elseif trigger =~ '^\->'
+		      let items = ['map()', 'reduce()']
+		    elseif trigger =~ '^\abc'
+		      let items = ['def', 'ghk']
+		    endif
+		    if items->len() > 0
+		      let startcol = trigger =~ '^/' ? col : col + len(trigger)
+		      call complete(startcol, items)
+		    endif
+		  endfunc
+		  inoremap <Tab> <Cmd>call CustomComplete()<CR>
+<
+
+                Parameters: ~
+                  • {lnum} (`integer?`)
+                  • {col} (`integer?`)
+
+                Return: ~
+                  (`table`)
+
 confirm({msg} [, {choices} [, {default} [, {type}]]])                *confirm()*
 		confirm() offers the user a dialog, from which a choice can be
 		made.  It returns the number of the choice.  For the first
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index ec139c1484..d7dbc350cf 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -3543,6 +3543,23 @@ A jump table for the options with a short description can be found at |Q_op|.
 	and there is a letter before it, the completed part is made uppercase.
 	With 'noinfercase' the match is used as-is.
 
+						*'isexpand'* *'ise'*
+'isexpand' 'ise'	string	(default "")
+			global or local to buffer |global-local|
+	Defines characters and patterns for completion in insert mode. Used by
+	the |complete_match()| function to determine the starting position for
+	completion. This is a comma-separated list of triggers. Each trigger
+	can be:
+	- A single character like "." or "/"
+	- A sequence of characters like "->", "/*", or "/**"
+
+	Note: Use "\\," to add a literal comma as trigger character, see
+	|option-backslash|.
+
+	Examples: >vim
+	    set isexpand=.,->,/*,\\,
+<
+
 						*'isfname'* *'isf'*
 'isfname' 'isf'		string	(default for Windows:
                              "@,48-57,/,\,.,-,_,+,,,#,$,%,{,},[,],@-@,!,~,="
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index 916fd9e2e2..cc37197a79 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -934,6 +934,8 @@ Insert mode completion:				*completion-functions*
 	complete_add()		add to found matches
 	complete_check()	check if completion should be aborted
 	complete_info()		get current completion information
+	complete_match()	get insert completion start match col and
+				trigger text
 	pumvisible()		check if the popup menu is displayed
 	pum_getpos()		position and size of popup menu if visible
 
diff --git a/runtime/lua/vim/_meta/options.lua b/runtime/lua/vim/_meta/options.lua
index e103226a44..5115c925be 100644
--- a/runtime/lua/vim/_meta/options.lua
+++ b/runtime/lua/vim/_meta/options.lua
@@ -3438,6 +3438,31 @@ vim.o.inf = vim.o.infercase
 vim.bo.infercase = vim.o.infercase
 vim.bo.inf = vim.bo.infercase
 
+--- Defines characters and patterns for completion in insert mode. Used by
+--- the `complete_match()` function to determine the starting position for
+--- completion. This is a comma-separated list of triggers. Each trigger
+--- can be:
+--- - A single character like "." or "/"
+--- - A sequence of characters like "->", "/*", or "/**"
+---
+--- Note: Use "\\," to add a literal comma as trigger character, see
+--- `option-backslash`.
+---
+--- Examples:
+---
+--- ```vim
+---     set isexpand=.,->,/*,\\,
+--- ```
+---
+---
+--- @type string
+vim.o.isexpand = ""
+vim.o.ise = vim.o.isexpand
+vim.bo.isexpand = vim.o.isexpand
+vim.bo.ise = vim.bo.isexpand
+vim.go.isexpand = vim.o.isexpand
+vim.go.ise = vim.go.isexpand
+
 --- The characters specified by this option are included in file names and
 --- path names.  Filenames are used for commands like "gf", "[i" and in
 --- the tags file.  It is also used for "\f" in a `pattern`.
diff --git a/runtime/lua/vim/_meta/vimfn.lua b/runtime/lua/vim/_meta/vimfn.lua
index 5ba94663cd..30bd45c889 100644
--- a/runtime/lua/vim/_meta/vimfn.lua
+++ b/runtime/lua/vim/_meta/vimfn.lua
@@ -1109,6 +1109,53 @@ function vim.fn.complete_check() end
 --- @return table
 function vim.fn.complete_info(what) end
 
+--- Searches backward from the given position and returns a List
+--- of matches according to the 'isexpand' option. When no
+--- arguments are provided, uses the current cursor position.
+---
+--- Each match is represented as a List containing
+--- [startcol, trigger_text] where:
+--- - startcol: column position where completion should start,
+---   or -1 if no trigger position is found. For multi-character
+---   triggers, returns the column of the first character.
+--- - trigger_text: the matching trigger string from 'isexpand',
+---   or empty string if no match was found or when using the
+---   default 'iskeyword' pattern.
+---
+--- When 'isexpand' is empty, uses the 'iskeyword' pattern
+--- "\k\+$" to find the start of the current keyword.
+---
+--- Examples: >vim
+---   set isexpand=.,->,/,/*,abc
+---   func CustomComplete()
+---     let res = complete_match()
+---     if res->len() == 0 | return | endif
+---     let [col, trigger] = res[0]
+---     let items = []
+---     if trigger == '/*'
+---       let items = ['/** */']
+---     elseif trigger == '/'
+---       let items = ['/*! */', '// TODO:', '// fixme:']
+---     elseif trigger == '.'
+---       let items = ['length()']
+---     elseif trigger =~ '^\->'
+---       let items = ['map()', 'reduce()']
+---     elseif trigger =~ '^\abc'
+---       let items = ['def', 'ghk']
+---     endif
+---     if items->len() > 0
+---       let startcol = trigger =~ '^/' ? col : col + len(trigger)
+---       call complete(startcol, items)
+---     endif
+---   endfunc
+---   inoremap <Tab> <Cmd>call CustomComplete()<CR>
+--- <
+---
+--- @param lnum? integer
+--- @param col? integer
+--- @return table
+function vim.fn.complete_match(lnum, col) end
+
 --- confirm() offers the user a dialog, from which a choice can be
 --- made.  It returns the number of the choice.  For the first
 --- choice this is 1.
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index 9af414d909..eed625a7c7 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -1,7 +1,7 @@
 " These commands create the option window.
 "
 " Maintainer:	The Vim Project <https://github.com/vim/vim>
-" Last Change:	2025 Apr 07
+" Last Change:	2025 Apr 24
 " Former Maintainer:	Bram Moolenaar <Bram@vim.org>
 
 " If there already is an option window, jump to that one.
@@ -1102,6 +1102,8 @@ call <SID>AddOption("isfname", gettext("specifies the characters in a file name"
 call <SID>OptionG("isf", &isf)
 call <SID>AddOption("isident", gettext("specifies the characters in an identifier"))
 call <SID>OptionG("isi", &isi)
+call <SID>AddOption("isexpand", gettext("defines trigger strings for complete_match()"))
+call append("$", "\t" .. s:local_to_buffer)
 call <SID>AddOption("iskeyword", gettext("specifies the characters in a keyword"))
 call append("$", "\t" .. s:local_to_buffer)
 call <SID>OptionL("isk")
diff --git a/src/nvim/buffer.c b/src/nvim/buffer.c
index 5fec2f1211..9d4365cdfc 100644
--- a/src/nvim/buffer.c
+++ b/src/nvim/buffer.c
@@ -2083,6 +2083,7 @@ void free_buf_options(buf_T *buf, bool free_p_ff)
   clear_string_option(&buf->b_p_cinw);
   clear_string_option(&buf->b_p_cot);
   clear_string_option(&buf->b_p_cpt);
+  clear_string_option(&buf->b_p_ise);
   clear_string_option(&buf->b_p_cfu);
   callback_free(&buf->b_cfu_cb);
   clear_string_option(&buf->b_p_ofu);
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 3866a0bea5..b3335aac44 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -558,6 +558,7 @@ struct file_buffer {
   char *b_p_fo;                 ///< 'formatoptions'
   char *b_p_flp;                ///< 'formatlistpat'
   int b_p_inf;                  ///< 'infercase'
+  char *b_p_ise;                ///< 'isexpand' local value
   char *b_p_isk;                ///< 'iskeyword'
   char *b_p_def;                ///< 'define' local value
   char *b_p_inc;                ///< 'include'
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 0013134857..eae54ca59a 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -1477,6 +1477,57 @@ M.funcs = {
     returns = 'table',
     signature = 'complete_info([{what}])',
   },
+  complete_match = {
+    args = { 0, 2 },
+    base = 0,
+    desc = [=[
+      Searches backward from the given position and returns a List
+      of matches according to the 'isexpand' option. When no
+      arguments are provided, uses the current cursor position.
+
+      Each match is represented as a List containing
+      [startcol, trigger_text] where:
+      - startcol: column position where completion should start,
+        or -1 if no trigger position is found. For multi-character
+        triggers, returns the column of the first character.
+      - trigger_text: the matching trigger string from 'isexpand',
+        or empty string if no match was found or when using the
+        default 'iskeyword' pattern.
+
+      When 'isexpand' is empty, uses the 'iskeyword' pattern
+      "\k\+$" to find the start of the current keyword.
+
+      Examples: >vim
+        set isexpand=.,->,/,/*,abc
+        func CustomComplete()
+          let res = complete_match()
+          if res->len() == 0 | return | endif
+          let [col, trigger] = res[0]
+          let items = []
+          if trigger == '/*'
+            let items = ['/** */']
+          elseif trigger == '/'
+            let items = ['/*! */', '// TODO:', '// fixme:']
+          elseif trigger == '.'
+            let items = ['length()']
+          elseif trigger =~ '^\->'
+            let items = ['map()', 'reduce()']
+          elseif trigger =~ '^\abc'
+            let items = ['def', 'ghk']
+          endif
+          if items->len() > 0
+            let startcol = trigger =~ '^/' ? col : col + len(trigger)
+            call complete(startcol, items)
+          endif
+        endfunc
+        inoremap <Tab> <Cmd>call CustomComplete()<CR>
+      <
+    ]=],
+    name = 'complete_match',
+    params = { { 'lnum', 'integer' }, { 'col', 'integer' } },
+    returns = 'table',
+    signature = 'complete_match([{lnum}, {col}])',
+  },
   confirm = {
     args = { 1, 4 },
     base = 1,
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 453d9535c5..248da8ae82 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -3081,6 +3081,81 @@ void f_complete_check(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   RedrawingDisabled = saved;
 }
 
+/// Add match item to the return list.
+static void add_match_to_list(typval_T *rettv, char *str, int pos)
+{
+  list_T *match = tv_list_alloc(2);
+  tv_list_append_number(match, pos + 1);
+  tv_list_append_string(match, str, -1);
+  tv_list_append_list(rettv->vval.v_list, match);
+}
+
+/// "complete_match()" function
+void f_complete_match(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
+{
+  tv_list_alloc_ret(rettv, kListLenUnknown);
+
+  char *ise = curbuf->b_p_ise[0] != NUL ? curbuf->b_p_ise : p_ise;
+
+  linenr_T lnum = 0;
+  colnr_T col = 0;
+  char part[MAXPATHL];
+  if (argvars[0].v_type == VAR_UNKNOWN) {
+    lnum = curwin->w_cursor.lnum;
+    col = curwin->w_cursor.col;
+  } else if (argvars[1].v_type == VAR_UNKNOWN) {
+    emsg(_(e_invarg));
+    return;
+  } else {
+    lnum = (linenr_T)tv_get_number(&argvars[0]);
+    col = (colnr_T)tv_get_number(&argvars[1]);
+    if (lnum < 1 || lnum > curbuf->b_ml.ml_line_count) {
+      semsg(_(e_invalid_line_number_nr), lnum);
+      return;
+    }
+    if (col < 1 || col > ml_get_buf_len(curbuf, lnum)) {
+      semsg(_(e_invalid_column_number_nr), col + 1);
+      return;
+    }
+  }
+
+  char *line = ml_get_buf(curbuf, lnum);
+  if (line == NULL) {
+    return;
+  }
+
+  char *before_cursor = xstrnsave(line, (size_t)col);
+
+  if (ise == NULL || *ise == NUL) {
+    regmatch_T regmatch;
+    regmatch.regprog = vim_regcomp("\\k\\+$", RE_MAGIC);
+    if (regmatch.regprog != NULL) {
+      if (vim_regexec_nl(&regmatch, before_cursor, (colnr_T)0)) {
+        char *trig = xstrnsave(regmatch.startp[0], (size_t)(regmatch.endp[0] - regmatch.startp[0]));
+        int bytepos = (int)(regmatch.startp[0] - before_cursor);
+        add_match_to_list(rettv, trig, bytepos);
+        xfree(trig);
+      }
+      vim_regfree(regmatch.regprog);
+    }
+  } else {
+    char *p = ise;
+    char *cur_end = before_cursor + (int)strlen(before_cursor);
+
+    while (*p != NUL) {
+      size_t len = copy_option_part(&p, part, MAXPATHL, ",");
+      if (len > 0 && (int)len <= col) {
+        if (strncmp(cur_end - len, part, len) == 0) {
+          int bytepos = col - (int)len;
+          add_match_to_list(rettv, part, bytepos);
+        }
+      }
+    }
+  }
+
+  xfree(before_cursor);
+}
+
 /// Return Insert completion mode name string
 static char *ins_compl_mode(void)
 {
diff --git a/src/nvim/option.c b/src/nvim/option.c
index bdf418c1f8..ae4520d9e1 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -4462,6 +4462,8 @@ void *get_varp_scope_from(vimoption_T *p, int opt_flags, buf_T *buf, win_T *win)
       return &(buf->b_p_inc);
     case kOptCompleteopt:
       return &(buf->b_p_cot);
+    case kOptIsexpand:
+      return &(buf->b_p_ise);
     case kOptDictionary:
       return &(buf->b_p_dict);
     case kOptThesaurus:
@@ -4547,6 +4549,8 @@ void *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
     return *buf->b_p_inc != NUL ? &(buf->b_p_inc) : p->var;
   case kOptCompleteopt:
     return *buf->b_p_cot != NUL ? &(buf->b_p_cot) : p->var;
+  case kOptIsexpand:
+    return *buf->b_p_ise != NUL ? &(buf->b_p_ise) : p->var;
   case kOptDictionary:
     return *buf->b_p_dict != NUL ? &(buf->b_p_dict) : p->var;
   case kOptThesaurus:
@@ -5238,6 +5242,7 @@ void buf_copy_options(buf_T *buf, int flags)
       buf->b_cot_flags = 0;
       buf->b_p_dict = empty_string_option;
       buf->b_p_tsr = empty_string_option;
+      buf->b_p_ise = empty_string_option;
       buf->b_p_tsrfu = empty_string_option;
       buf->b_p_qe = xstrdup(p_qe);
       COPY_OPT_SCTX(buf, kBufOptQuoteescape);
diff --git a/src/nvim/option_vars.h b/src/nvim/option_vars.h
index d8d3e1e124..16b009fa73 100644
--- a/src/nvim/option_vars.h
+++ b/src/nvim/option_vars.h
@@ -374,6 +374,7 @@ EXTERN int p_is;                ///< 'incsearch'
 EXTERN char *p_inde;            ///< 'indentexpr'
 EXTERN char *p_indk;            ///< 'indentkeys'
 EXTERN char *p_icm;             ///< 'inccommand'
+EXTERN char *p_ise;             ///< 'isexpand'
 EXTERN char *p_isf;             ///< 'isfname'
 EXTERN char *p_isi;             ///< 'isident'
 EXTERN char *p_isk;             ///< 'iskeyword'
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index ed1cf175be..4a73846ad2 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -4634,6 +4634,33 @@ local options = {
       type = 'boolean',
       immutable = true,
     },
+    {
+      abbreviation = 'ise',
+      cb = 'did_set_isexpand',
+      defaults = '',
+      deny_duplicates = true,
+      desc = [=[
+        Defines characters and patterns for completion in insert mode. Used by
+        the |complete_match()| function to determine the starting position for
+        completion. This is a comma-separated list of triggers. Each trigger
+        can be:
+        - A single character like "." or "/"
+        - A sequence of characters like "->", "/*", or "/**"
+
+        Note: Use "\\," to add a literal comma as trigger character, see
+        |option-backslash|.
+
+        Examples: >vim
+            set isexpand=.,->,/*,\\,
+        <
+      ]=],
+      full_name = 'isexpand',
+      list = 'onecomma',
+      scope = { 'global', 'buf' },
+      short_desc = N_('Defines characters and patterns for completion in insert mode'),
+      type = 'string',
+      varname = 'p_ise',
+    },
     {
       abbreviation = 'isf',
       cb = 'did_set_isopt',
diff --git a/src/nvim/optionstr.c b/src/nvim/optionstr.c
index e26099d71b..c66526318e 100644
--- a/src/nvim/optionstr.c
+++ b/src/nvim/optionstr.c
@@ -85,6 +85,7 @@ void didset_string_options(void)
   check_str_opt(kOptBackupcopy, NULL);
   check_str_opt(kOptBelloff, NULL);
   check_str_opt(kOptCompletefuzzycollect, NULL);
+  check_str_opt(kOptIsexpand, NULL);
   check_str_opt(kOptCompleteopt, NULL);
   check_str_opt(kOptSessionoptions, NULL);
   check_str_opt(kOptViewoptions, NULL);
@@ -1316,6 +1317,44 @@ const char *did_set_inccommand(optset_T *args FUNC_ATTR_UNUSED)
   return did_set_str_generic(args);
 }
 
+/// The 'isexpand' option is changed.
+const char *did_set_isexpand(optset_T *args)
+{
+  char *ise = p_ise;
+  char *p;
+  bool last_was_comma = false;
+
+  if (args->os_flags & OPT_LOCAL) {
+    ise = curbuf->b_p_ise;
+  }
+
+  for (p = ise; *p != NUL;) {
+    if (*p == '\\' && p[1] == ',') {
+      p += 2;
+      last_was_comma = false;
+      continue;
+    }
+
+    if (*p == ',') {
+      if (last_was_comma) {
+        return e_invarg;
+      }
+      last_was_comma = true;
+      p++;
+      continue;
+    }
+
+    last_was_comma = false;
+    MB_PTR_ADV(p);
+  }
+
+  if (last_was_comma) {
+    return e_invarg;
+  }
+
+  return NULL;
+}
+
 /// The 'iskeyword' option is changed.
 const char *did_set_iskeyword(optset_T *args)
 {
diff --git a/test/old/testdir/gen_opt_test.vim b/test/old/testdir/gen_opt_test.vim
index 168a38e665..16e165cc13 100644
--- a/test/old/testdir/gen_opt_test.vim
+++ b/test/old/testdir/gen_opt_test.vim
@@ -261,6 +261,7 @@ let test_values = {
       "\ 'imactivatekey': [['', 'S-space'], ['xxx']],
       \ 'isfname': [['', '@', '@,48-52'], ['xxx', '@48']],
       \ 'isident': [['', '@', '@,48-52'], ['xxx', '@48']],
+      \ 'isexpand': [['', '.,->', '/,/*,\\,'], [',,', '\\,,']],
       \ 'iskeyword': [['', '@', '@,48-52'], ['xxx', '@48']],
       \ 'isprint': [['', '@', '@,48-52'], ['xxx', '@48']],
       \ 'jumpoptions': [['', 'stack'], ['xxx']],
diff --git a/test/old/testdir/test_ins_complete.vim b/test/old/testdir/test_ins_complete.vim
index ded4f7392e..9bc004733b 100644
--- a/test/old/testdir/test_ins_complete.vim
+++ b/test/old/testdir/test_ins_complete.vim
@@ -3598,4 +3598,86 @@ func Test_nearest_cpt_option()
   delfunc PrintMenuWords
 endfunc
 
+func Test_complete_match()
+  set isexpand=.,/,->,abc,/*,_
+  func TestComplete()
+    let res = complete_match()
+    if res->len() == 0
+      return
+    endif
+    let [startcol, expandchar] = res[0]
+
+    if startcol >= 0
+      let line = getline('.')
+
+      let items = []
+      if expandchar == '/*'
+        let items = ['/** */']
+      elseif expandchar =~ '^/'
+        let items = ['/*! */', '// TODO:', '// fixme:']
+      elseif expandchar =~ '^\.' && startcol < 4
+        let items = ['length()', 'push()', 'pop()', 'slice()']
+      elseif expandchar =~ '^\.' && startcol > 4
+        let items = ['map()', 'filter()', 'reduce()']
+      elseif expandchar =~ '^\abc'
+        let items = ['def', 'ghk']
+      elseif expandchar =~ '^\->'
+        let items = ['free()', 'xfree()']
+      else
+        let items = ['test1', 'test2', 'test3']
+      endif
+
+      call complete(expandchar =~ '^/' ? startcol : startcol + strlen(expandchar), items)
+    endif
+  endfunc
+
+  new
+  inoremap <buffer> <F5> <cmd>call TestComplete()<CR>
+
+  call feedkeys("S/*\<F5>\<C-Y>", 'tx')
+  call assert_equal('/** */', getline('.'))
+
+  call feedkeys("S/\<F5>\<C-N>\<C-Y>", 'tx')
+  call assert_equal('// TODO:', getline('.'))
+
+  call feedkeys("Swp.\<F5>\<C-N>\<C-Y>", 'tx')
+  call assert_equal('wp.push()', getline('.'))
+
+  call feedkeys("Swp.property.\<F5>\<C-N>\<C-Y>", 'tx')
+  call assert_equal('wp.property.filter()', getline('.'))
+
+  call feedkeys("Sp->\<F5>\<C-N>\<C-Y>", 'tx')
+  call assert_equal('p->xfree()', getline('.'))
+
+  call feedkeys("Swp->property.\<F5>\<C-Y>", 'tx')
+  call assert_equal('wp->property.map()', getline('.'))
+
+  call feedkeys("Sabc\<F5>\<C-Y>", 'tx')
+  call assert_equal('abcdef', getline('.'))
+
+  call feedkeys("S_\<F5>\<C-Y>", 'tx')
+  call assert_equal('_test1', getline('.'))
+
+  set ise&
+  call feedkeys("Sabc \<ESC>:let g:result=complete_match()\<CR>", 'tx')
+  call assert_equal([[1, 'abc']], g:result)
+
+  call assert_fails('call complete_match(99, 0)', 'E966:')
+  call assert_fails('call complete_match(1, 99)', 'E964:')
+  call assert_fails('call complete_match(1)', 'E474:')
+
+  set ise=你好,好
+  call feedkeys("S你好 \<ESC>:let g:result=complete_match()\<CR>", 'tx')
+  call assert_equal([[1, '你好'], [4, '好']], g:result)
+
+  set ise=\\,,->
+  call feedkeys("Sabc, \<ESC>:let g:result=complete_match()\<CR>", 'tx')
+  call assert_equal([[4, ',']], g:result)
+
+  bw!
+  unlet g:result
+  set isexpand&
+  delfunc TestComplete
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab nofoldenable