diff --git a/src/testdir/emoji_list.vim b/src/testdir/emoji_list.vim
new file mode 100644
index 0000000..e6a73c3
--- /dev/null
+++ b/src/testdir/emoji_list.vim
@@ -0,0 +1,22 @@
+" Script to fill the window with emoji characters, one per line.
+
+if &modified
+  new
+else
+  enew
+endif
+
+" Use a compiled Vim9 function for speed
+def DoIt()
+  let lnum = 1
+  for c in range(0x100, 0x1ffff)
+    let cs = nr2char(c)
+    if charclass(cs) == 3
+      setline(lnum, '|' .. cs .. '| ' .. strwidth(cs))
+      lnum += 1
+    endif
+  endfor
+enddef
+
+call DoIt()
+set nomodified
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index e15199b..fd9057d 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -2077,6 +2077,13 @@
   set encoding=utf-8
 endfunc
 
+func Test_charclass()
+  call assert_equal(0, charclass(' '))
+  call assert_equal(1, charclass('.'))
+  call assert_equal(2, charclass('x'))
+  call assert_equal(3, charclass("\u203c"))
+endfunc
+
 func Test_eventhandler()
   call assert_equal(0, eventhandler())
 endfunc