Re: [PATCH 05/10] t0301: another fix for Windows compatibility

[Junio C Hamano <gitster@pobox.com>]

"Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
writes:

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> Just like 0fdcfa2f9f5 (t0301: fixes for windows compatibility,
> 2021-09-14) explained, we should not call `mkdir -m<mode>` in the test
> suite because that would fail on Windows (because Windows has a much
> more powerful permission system that cannot be mapped into the simpler
> user/group/other read/write/execute model).

But in this case, we are emulating "mkdir -m 700" that is expressed
in a very simpler world view of ugo=rwx with a much more powerful
permission system, isn't it?  If something is more powerful, it
should be easy/possible to emulate a simpler system, I would naively
think.

In any case, a more productive than rethinking the "can we express
what mkdir -m <mode>, which is a construct in a simpler world, wants
to do in terms of a much more powerful permission system?" would be
to see if the test linter can be taught about this particular rule.

It is easy to forget that there is a platform we care about whose
testing environment that emulates POSIX does not like "mkdir -m
700", and it is a bit too much to burden developers to remember.

> There was one forgotten instance of this which was hidden by a `SYMLINK`
> prerequisite. Currently, this prevents this test case from being
> executed on Windows, but with the upcoming support for symbolic links,
> it would become a problem.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  t/t0301-credential-cache.sh | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/t/t0301-credential-cache.sh b/t/t0301-credential-cache.sh
> index dc30289f75..6f7cfd9e33 100755
> --- a/t/t0301-credential-cache.sh
> +++ b/t/t0301-credential-cache.sh
> @@ -123,7 +123,8 @@ test_expect_success SYMLINKS 'use user socket if user directory is a symlink to
>  		rmdir \"\$HOME/dir/\" &&
>  		rm \"\$HOME/.git-credential-cache\"
>  	" &&
> -	mkdir -p -m 700 "$HOME/dir/" &&
> +	mkdir -p "$HOME/dir/" &&
> +	chmod 700 "$HOME/dir/" &&

That "mkdir -p -m 700" is a no-no while "mkdir -p" followed by
"chmod 700" is OK is a bit puzzling, but I assume $HOME does exist
in the testing envioronment, so this new sequence should be
equivalent in the simpler permission system.  If it works fine on
Windows, that is great.

>  	ln -s "$HOME/dir" "$HOME/.git-credential-cache" &&
>  	check approve cache <<-\EOF &&
>  	protocol=https