vim-patch:8.2.3989: some insert completion code is not tested

Problem:    Some insert completion code is not tested.
Solution:   Add a few tests.  Refactor thesaurus completion. (Yegappan
            Lakshmanan, closes vim/vim#9460)
https://github.com/vim/vim/commit/e982586f8eebf2b055987218f6d3f7a084c4bf69

vim-patch:9.0.0254: typo in function name

Problem:    Typo in function name.
Solution:   Rename the function. (closes vim/vim#10971)
https://github.com/vim/vim/commit/5fb3aabc2b0edd5573e107bb3bc103c348771f61

3 files changed, 185 insertions, 36 deletions

diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index d22c1ff980..21285a4365 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -1005,6 +1005,8 @@ static dict_T *ins_compl_dict_alloc(compl_T *match)
   return dict;
 }
 
+/// Trigger the CompleteChanged autocmd event. Invoked each time the Insert mode
+/// completion menu is changed.
 static void trigger_complete_changed_event(int cur)
 {
   static bool recursive = false;
@@ -1181,8 +1183,8 @@ void ins_compl_show_pum(void)
 #define DICT_FIRST      (1)     ///< use just first element in "dict"
 #define DICT_EXACT      (2)     ///< "dict" is the exact name of a file
 
-/// Add any identifiers that match the given pattern in the list of dictionary
-/// files "dict_start" to the list of completions.
+/// Add any identifiers that match the given pattern "pat" in the list of
+/// dictionary files "dict_start" to the list of completions.
 ///
 /// @param flags      DICT_FIRST and/or DICT_EXACT
 /// @param thesaurus  Thesaurus completion
@@ -1283,6 +1285,54 @@ theend:
   xfree(buf);
 }
 
+/// Add all the words in the line "*buf_arg" from the thesaurus file "fname"
+/// skipping the word at 'skip_word'.
+///
+/// @return  OK on success.
+static int thesaurus_add_words_in_line(char *fname, char_u **buf_arg, int dir, char_u *skip_word)
+{
+  int status = OK;
+
+  // Add the other matches on the line
+  char_u *ptr = *buf_arg;
+  while (!got_int) {
+    // Find start of the next word.  Skip white
+    // space and punctuation.
+    ptr = find_word_start(ptr);
+    if (*ptr == NUL || *ptr == NL) {
+      break;
+    }
+    char_u *wstart = ptr;
+
+    // Find end of the word.
+    // Japanese words may have characters in
+    // different classes, only separate words
+    // with single-byte non-word characters.
+    while (*ptr != NUL) {
+      const int l = utfc_ptr2len((const char *)ptr);
+
+      if (l < 2 && !vim_iswordc(*ptr)) {
+        break;
+      }
+      ptr += l;
+    }
+
+    // Add the word. Skip the regexp match.
+    if (wstart != skip_word) {
+      status = ins_compl_add_infercase(wstart, (int)(ptr - wstart), p_ic,
+                                       (char_u *)fname, dir, false);
+      if (status == FAIL) {
+        break;
+      }
+    }
+  }
+
+  *buf_arg = ptr;
+  return status;
+}
+
+/// Process "count" dictionary/thesaurus "files" and add the text matching
+/// "regmatch".
 static void ins_compl_files(int count, char **files, int thesaurus, int flags, regmatch_T *regmatch,
                             char_u *buf, Direction *dir)
   FUNC_ATTR_NONNULL_ARG(2, 7)
@@ -1320,38 +1370,10 @@ static void ins_compl_files(int count, char **files, int thesaurus, int flags, r
                                         (int)(ptr - regmatch->startp[0]),
                                         p_ic, (char_u *)files[i], *dir, false);
         if (thesaurus) {
-          char_u *wstart;
-
-          // Add the other matches on the line
+          // For a thesaurus, add all the words in the line
           ptr = buf;
-          while (!got_int) {
-            // Find start of the next word.  Skip white
-            // space and punctuation.
-            ptr = find_word_start(ptr);
-            if (*ptr == NUL || *ptr == NL) {
-              break;
-            }
-            wstart = ptr;
-
-            // Find end of the word.
-            // Japanese words may have characters in
-            // different classes, only separate words
-            // with single-byte non-word characters.
-            while (*ptr != NUL) {
-              const int l = utfc_ptr2len((char *)ptr);
-
-              if (l < 2 && !vim_iswordc(*ptr)) {
-                break;
-              }
-              ptr += l;
-            }
-
-            // Add the word. Skip the regexp match.
-            if (wstart != regmatch->startp[0]) {
-              add_r = ins_compl_add_infercase(wstart, (int)(ptr - wstart),
-                                              p_ic, (char_u *)files[i], *dir, false);
-            }
-          }
+          add_r = thesaurus_add_words_in_line(files[i], &ptr, *dir,
+                                              regmatch->startp[0]);
         }
         if (add_r == OK) {
           // if dir was BACKWARD then honor it just once
@@ -1536,12 +1558,12 @@ int ins_compl_bs(void)
 
   xfree(compl_leader);
   compl_leader = vim_strnsave(line + compl_col, (size_t)(p_off - (ptrdiff_t)compl_col));
+
   ins_compl_new_leader();
   if (compl_shown_match != NULL) {
     // Make sure current match is not a hidden item.
     compl_curr_match = compl_shown_match;
   }
-
   return NUL;
 }
 
@@ -2401,6 +2423,8 @@ static char_u *ins_compl_mode(void)
   return (char_u *)"";
 }
 
+/// Assign the sequence number to all the completion matches which don't have
+/// one assigned yet.
 static void ins_compl_update_sequence_numbers(void)
 {
   int number = 0;
@@ -4154,6 +4178,7 @@ int ins_complete(int c, bool enable_pum)
   return OK;
 }
 
+/// Remove (if needed) and show the popup menu
 static void show_pum(int prev_w_wrow, int prev_w_leftcol)
 {
   // RedrawingDisabled may be set when invoked through complete().
diff --git a/src/nvim/testdir/test_edit.vim b/src/nvim/testdir/test_edit.vim
index fa288df0d9..679b877ef6 100644
--- a/src/nvim/testdir/test_edit.vim
+++ b/src/nvim/testdir/test_edit.vim
@@ -730,8 +730,13 @@ func Test_edit_CTRL_N()
     call feedkeys("Ii\<c-n>\<cr>\<esc>", "tnix")
     call feedkeys("ILO\<c-n>\<cr>\<esc>", 'tnix')
     call assert_equal(['INFER', 'loWER', 'infer', 'LOWER', '', ''], getline(1, '$'), e)
-
-    set noignorecase noinfercase complete&
+    set noignorecase noinfercase
+    %d
+    call setline(1, ['one word', 'two word'])
+    exe "normal! Goo\<C-P>\<C-X>\<C-P>"
+    call assert_equal('one word', getline(3))
+    %d
+    set complete&
     bw!
   endfor
 endfunc
@@ -897,6 +902,24 @@ func Test_edit_CTRL_T()
   bw!
 endfunc
 
+" Test thesaurus completion with different encodings
+func Test_thesaurus_complete_with_encoding()
+  call writefile(['angry furious mad enraged'], 'Xthesaurus')
+  set thesaurus=Xthesaurus
+  " for e in ['latin1', 'utf-8']
+  for e in ['utf-8']
+    exe 'set encoding=' .. e
+    new
+    call setline(1, 'mad')
+    call cursor(1, 1)
+    call feedkeys("A\<c-x>\<c-t>\<cr>\<esc>", 'tnix')
+    call assert_equal(['mad', ''], getline(1, '$'))
+    bw!
+  endfor
+  set thesaurus=
+  call delete('Xthesaurus')
+endfunc
+
 " Test 'thesaurusfunc'
 func MyThesaurus(findstart, base)
   let mythesaurus = [
diff --git a/src/nvim/testdir/test_ins_complete.vim b/src/nvim/testdir/test_ins_complete.vim
index 8f7d2cb278..914d818eef 100644
--- a/src/nvim/testdir/test_ins_complete.vim
+++ b/src/nvim/testdir/test_ins_complete.vim
@@ -682,6 +682,21 @@ func Test_complete_func_error()
   call assert_equal([], complete_info(['items']).items)
 endfunc
 
+" Test for recursively starting completion mode using complete()
+func Test_recursive_complete_func()
+  func ListColors()
+    call complete(5, ["red", "blue"])
+    return ''
+  endfunc
+  new
+  call setline(1, ['a1', 'a2'])
+  set complete=.
+  exe "normal Goa\<C-X>\<C-L>\<C-R>=ListColors()\<CR>\<C-N>"
+  call assert_equal('a2blue', getline(3))
+  delfunc ListColors
+  bw!
+endfunc
+
 " Test for completing words following a completed word in a line
 func Test_complete_wrapscan()
   " complete words from another buffer
@@ -905,6 +920,92 @@ func Test_issue_7021()
   set completeslash=
 endfunc
 
+" Test for 'longest' setting in 'completeopt' with latin1 and utf-8 encodings
+func Test_complete_longest_match()
+  " for e in ['latin1', 'utf-8']
+  for e in ['utf-8']
+    exe 'set encoding=' .. e
+    new
+    set complete=.
+    set completeopt=menu,longest
+    call setline(1, ['pfx_a1', 'pfx_a12', 'pfx_a123', 'pfx_b1'])
+    exe "normal Gopfx\<C-P>"
+    call assert_equal('pfx_', getline(5))
+    bw!
+  endfor
+
+  " Test for completing additional words with longest match set
+  new
+  call setline(1, ['abc1', 'abd2'])
+  exe "normal Goab\<C-P>\<C-X>\<C-P>"
+  call assert_equal('ab', getline(3))
+  bw!
+  set complete& completeopt&
+endfunc
+
+" Test for removing the first displayed completion match and selecting the
+" match just before that.
+func Test_complete_erase_firstmatch()
+  new
+  call setline(1, ['a12', 'a34', 'a56'])
+  set complete=.
+  exe "normal Goa\<C-P>\<BS>\<BS>3\<CR>"
+  call assert_equal('a34', getline('$'))
+  set complete&
+  bw!
+endfunc
+
+" Test for completing whole lines from unloaded buffers
+func Test_complete_wholeline_unloadedbuf()
+  call writefile(['a line1', 'a line2', 'a line3'], "Xfile1")
+  edit Xfile1
+  enew
+  set complete=u
+  exe "normal! ia\<C-X>\<C-L>\<C-P>"
+  call assert_equal('a line2', getline(1))
+  %d
+  " completing from an unlisted buffer should fail
+  bdel Xfile1
+  exe "normal! ia\<C-X>\<C-L>\<C-P>"
+  call assert_equal('a', getline(1))
+  set complete&
+  %bw!
+  call delete("Xfile1")
+endfunc
+
+" Test for completing whole lines from unlisted buffers
+func Test_complete_wholeline_unlistedbuf()
+  call writefile(['a line1', 'a line2', 'a line3'], "Xfile1")
+  edit Xfile1
+  enew
+  set complete=U
+  " completing from a unloaded buffer should fail
+  exe "normal! ia\<C-X>\<C-L>\<C-P>"
+  call assert_equal('a', getline(1))
+  %d
+  bdel Xfile1
+  exe "normal! ia\<C-X>\<C-L>\<C-P>"
+  call assert_equal('a line2', getline(1))
+  set complete&
+  %bw!
+  call delete("Xfile1")
+endfunc
+
+" Test for adding a multibyte character using CTRL-L in completion mode
+func Test_complete_mbyte_char_add()
+  new
+  set complete=.
+  call setline(1, 'abė')
+  exe "normal! oa\<C-P>\<BS>\<BS>\<C-L>\<C-L>"
+  call assert_equal('abė', getline(2))
+  " Test for a leader with multibyte character
+  %d
+  call setline(1, 'abėĕ')
+  exe "normal! oabė\<C-P>"
+  call assert_equal('abėĕ', getline(2))
+  bw!
+endfunc
+
 " Test to ensure 'Scanning...' messages are not recorded in messages history
 func Test_z1_complete_no_history()
   new