patch 9.1.0805: tests: minor issues in gen_opt_test.vim

Problem:  tests: minor issues in gen_opt_test.vim
Solution: fix restore value for 'undolevels', fix comment, fix
          wrong cpo value, add equality test for global-local options on
          switchback (Milly).

closes: #15913

Signed-off-by: Milly <milly.ca@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: Milly

src/testdir/gen_opt_test.vim

@@ -1,7 +1,7 @@
 " Script to generate src/testdir/opt_test.vim from src/optiondefs.h and
 " runtime/doc/options.txt
 
-set cpo=&vim
+set cpo&vim
 
 " Only do this when build with the +eval feature.
 if 1
@@ -25,7 +25,7 @@ endwhile
 call extend(global_locals, #{
       \ scrolloff: -1,
       \ sidescrolloff: -1,
-      \ undolevels: -12345,
+      \ undolevels: -123456,
       \})
 
 " Get local-noglobal options.
@@ -56,7 +56,8 @@ let skip_setglobal_reasons = #{
       \ textwidth:	'TODO: fix missing error handling for setglobal',
       \}
 
-" The terminal size is restored at the end.
+" Script header.
+" The test values contains multibyte characters.
 let script = [
       \ '" DO NOT EDIT: Generated with gen_opt_test.vim',
       \ '" Used by test_options_all.vim.',
@@ -417,8 +418,9 @@ while 1
       endfor
       " Testing to clear the local value and switch back to the global value.
       if global_locals->has_key(fullname)
-	let swichback_val = global_locals[fullname]
-	call add(script, $'setlocal {opt}={swichback_val}')
+	let switchback_val = global_locals[fullname]
+	call add(script, $'setlocal {opt}={switchback_val}')
+	call add(script, $'call assert_equal(&g:{fullname}, &{fullname})')
       endif
     endfor
 

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    805,
 /**/
     804,
 /**/