From 0039a13fe4c24958685b2dba28f0442949e46b14 Mon Sep 17 00:00:00 2001
From: zeertzjq <zeertzjq@outlook.com>
Date: Sun, 26 Apr 2026 16:59:32 +0800
Subject: [PATCH] vim-patch:9.2.0395: tests: Test_backupskip() may read from
 $HOME (#39417)

Problem:  tests: Test_backupskip() may read from $HOME
Solution: Set $HOME to an empty value, use --clean
          (D Ben Knoble)

Even though we unset HOME, we can see via scriptnames that user files
are still sourced! One of my installed plugins warns when not compiled
with +python3, so this test has a "press Enter" prompt.

Use `--clean` like most other GetVimProg()'s do to fix it. Some tests
use `system()` instead, but that turns this test into a failure rather
than passing; I'm not sure why other tests don't suffer from this.

To prove to ourselves, we can use code like this:

    diff --git i/src/testdir/test_options.vim w/src/testdir/test_options.vim
    index a408e20e1..044364a54 100644
    --- i/src/testdir/test_options.vim
    +++ w/src/testdir/test_options.vim
    @@ -1179,6 +1179,7 @@ func Test_backupskip()
       " P_NODUP).  Run this in a separate instance and write v:errors in a file,
       " so that we see what happens on startup.
       let after =<< trim [CODE]
    +      call writefile([execute('scriptnames')], 'foo')
           let bsklist = split(&backupskip, ',')
           call assert_equal(uniq(copy(bsklist)), bsklist)
           call writefile(['errors:'] + v:errors, 'Xtestout')
    @@ -1196,7 +1197,7 @@ func Test_backupskip()
       " unset $HOME, so that it won't try to read init files
       let saveenv['HOME'] = getenv("HOME")
       call setenv('HOME', v:null)
    -  exe 'silent !' . cmd
    +  exe 'silent !' . cmd .. ' --cmd "echo &rtp"'
       call assert_equal(['errors:'], readfile('Xtestout'))

       " restore environment variables

Here, that causes "foo" to include a bunch of files under ~/.vim. I'm
not sure why this happens, but lets paper over it for the test.

We can also tell that (orthogonal to --clean) setting HOME='' works too.
Let's do that in addition since unsetting HOME isn't quite enough.

closes: vim/vim#20051

https://github.com/vim/vim/commit/8d9c383aaff17f5991f739a6d0f06017022b2198

Co-authored-by: D. Ben Knoble <ben.knoble+github@gmail.com>
---
 test/old/testdir/test_options.vim | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/test/old/testdir/test_options.vim b/test/old/testdir/test_options.vim
index cbd1f74bd9..5a2d397b6e 100644
--- a/test/old/testdir/test_options.vim
+++ b/test/old/testdir/test_options.vim
@@ -1155,9 +1155,9 @@ func Test_backupskip()
       call writefile(['errors:'] + v:errors, 'Xtestout')
       qall
   [CODE]
-  call writefile(after, 'Xafter')
-  " let cmd = GetVimProg() . ' --not-a-term -S Xafter --cmd "set enc=utf8"'
-  let cmd = GetVimProg() . ' -S Xafter --cmd "set enc=utf8"'
+  call writefile(after, 'Xafter', 'D')
+  " let cmd = GetVimProg() . ' --clean --not-a-term -S Xafter --cmd "set enc=utf8"'
+  let cmd = GetVimProg() . ' --clean -S Xafter --cmd "set enc=utf8"'
 
   let saveenv = {}
   for var in ['TMPDIR', 'TMP', 'TEMP']
@@ -1165,9 +1165,9 @@ func Test_backupskip()
     call setenv(var, '/duplicate/path')
   endfor
 
-  " unset $HOME, so that it won't try to read init files
+  " set $HOME='', so that Vim won't try to read init files
   let saveenv['HOME'] = getenv("HOME")
-  call setenv('HOME', v:null)
+  call setenv('HOME', '')
   exe 'silent !' . cmd
   call assert_equal(['errors:'], readfile('Xtestout'))
 
@@ -1177,7 +1177,6 @@ func Test_backupskip()
   endfor
 
   call delete('Xtestout')
-  call delete('Xafter')
 
   " Duplicates should be filtered out (option has P_NODUP)
   let backupskip = &backupskip