patch 9.1.0629: Rename of pum hl_group is incomplete

Problem:  Rename of pum hl_group is incomplete in source.
Solution: Also rename the test function.  Rename to user_hlattr in code
          to avoid confusion with pum_extra.  Add test with matched text
          highlighting (zeertzjq).

closes: #15348

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_popup.vim b/src/testdir/test_popup.vim
index 67e600c..4c2fb45 100644
--- a/src/testdir/test_popup.vim
+++ b/src/testdir/test_popup.vim
@@ -1499,10 +1499,9 @@
   call StopVimInTerminal(buf)
 endfunc
 
-func Test_pum_extrahl()
+func Test_pum_user_hl_group()
   CheckScreendump
   let lines =<< trim END
-    hi StrikeFake ctermfg=9
     func CompleteFunc( findstart, base )
       if a:findstart
         return 0
@@ -1516,15 +1515,31 @@
     endfunc
     set completeopt=menu
     set completefunc=CompleteFunc
+
+    hi StrikeFake ctermfg=9
+    func HlMatch()
+      hi PmenuMatchSel  ctermfg=6 ctermbg=7 cterm=underline
+      hi PmenuMatch     ctermfg=4 ctermbg=225 cterm=underline
+    endfunc
   END
   call writefile(lines, 'Xscript', 'D')
   let buf = RunVimInTerminal('-S Xscript', {})
+
   call TermWait(buf)
-  call term_sendkeys(buf, "iaw\<C-X>\<C-u>")
-  call TermWait(buf, 50)
+  call term_sendkeys(buf, "Saw\<C-X>\<C-U>")
   call VerifyScreenDump(buf, 'Test_pum_highlights_12', {})
-  call term_sendkeys(buf, "\<C-E>\<Esc>u")
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
   call TermWait(buf)
+  call term_sendkeys(buf, ":call HlMatch()\<CR>")
+
+  call TermWait(buf)
+  call term_sendkeys(buf, "Saw\<C-X>\<C-U>")
+  call VerifyScreenDump(buf, 'Test_pum_highlights_13', {})
+  call term_sendkeys(buf, "\<C-N>")
+  call VerifyScreenDump(buf, 'Test_pum_highlights_14', {})
+  call term_sendkeys(buf, "\<C-E>\<Esc>")
+
   call StopVimInTerminal(buf)
 endfunc