Subject: Re: [PATCH] multi-pack-index: fix --object-dir from outside repo

From: Junio C Hamano <[email-masked]>
Date: Mon, 23 Aug 2021 09:16:01 -0700

Johannes Berg <[email-masked]> writes:

> On Mon, 2021-08-23 at 09:19 -0400, Derrick Stolee wrote:
>> 
>> We just add subshells this way:
>> 
>> test_expect_success 'test name' '
>> 	prep_step &&
>> 	(
>> 		# now in a subshell
>> 		cd wherever &&
>> 		do things
>> 		# don't need to cd again
>> 	) &&
>> 	continue test
>> '
>
> Sure. I know how to do subshells :)
>
> My point was that inside the subshell you cannot do test_path_is_file
> and similar, because the subshell didn't import the libs.

Everything the call to prep_step, and anything that came before that
call, did to the environment, like setting shell functions and
variables, is visible inside the ( ... subshell ... ).

> I was specifically asking Junio ;-)
>
> But realistically, if this is the requirement you want to impose, then
> you _cannot_ test for the segfault within git's test suite. Your loss.

With that "cannot", I think you are assuming too much.  

Because Git is a fairly long-lived project, we've had our share of
cases where we needed to test for bugs that happen only when outside
a repository.

And we have facility for just that, it's called "nongit" test helper
that comes from test-lib-functions.sh, which is dot-included already
so your subshells get it for free.

t5300-pack-object.sh, for example, wants to make sure that the "git
index-pack --stdin" command invoked in a directory that is not a
repository, but "git index-pack <packfile>" works outside a
repository, and has two tests that uses the nongit helper.

Thanks.