Re: [PATCH] t7900: use pwd -P in macOS maintenance test

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

Eric Sunshine <sunshine@sunshineco.com> writes:

>> -       pfx=$(cd "$HOME" && pwd) &&
>> +       pfx=$(cd "$HOME" && pwd -P) &&
>
> Okay, this seems like the minimum fix[*], and -P is POSIX.
>
> However, have you tested this on Windows? I ask because, despite the
> test's name, this and most of the tests in this script, are actually
> run on all platforms, and because `pwd` is overridden by a shell
> function for MinGW on Windows:
>
>     # t/test-lib.sh
>     ...
>     # git sees Windows-style pwd
>     pwd () {
>         builtin pwd -W
>     }
>
> My quick testing suggests that this patch's change might be problematic:
>
>     # on Windows
>     $ pwd
>     /home/me
>     $ pwd -W
>     C:/msys64/home/me
>     $ pwd -P
>     /home/me
>     $ pwd -W -P
>     /home/me

Because pwd emulation we use on Windows ignores -P the updated
caller, pfx with this change would not change the existing
behaviour.

How would one test this situation on Windows, I wonder?  Create a
directory that is pointed at by a symbolic link, and use it as the
test directory (either have the checkout there, or use --root to
have the trash directory there)?

> FOOTNOTES
>
> [*]: In the long run, a better fix would probably be for the tests to
> sanitize the output of the Git command, replacing (via `sed`) the
> actual emitted path with some placeholder, such as "%HOME%" or
> something, and then have the tests look for (`grep` or whatnot)
> needles using that literal placeholder rather than trying to perfectly
> match the path emitted by Git. This approach makes sense since these
> tests are about overall functionality of git-maintenance, not about
> the specific path in which the person happens to be running the tests.

Another approach may be to do a form of chdir that forces the shell
to figure out where it really is upfront at the beginning of a test
script, perhaps inside test-lib.sh which happend before anything
meaningful happens in the test (i.e. "cd -P ." or something).