Subject: Re: [RFC] test_when_finished in subshells

From: Junio C Hamano <[email-masked]>
Date: Fri, 04 Sep 2015 11:43:15 -0700

John Keeping <[email-masked]> writes:

> All are harmless at the moment and t7610 and t5801 can be fixed by
> moving the test_when_finished call out of the subshell relatively
> easily.
>
> t7800 (in its final test) calls test_config in a subshell which has cd'd
> into a submodule.
>
> Is this something worth worrying about, or is it sufficiently rare that
> we can live with the current behaviour?

Fixing the instances you found is good, obviously ;-).  Thanks for
working on this.

Even though the proposed detection is BASH-ism, I think it would not
hurt other shells (they obviously do not help you catch bugs, but
they would not misbehave as long as you make sure BASH_SUBSHELL is
either unset or set to 0 at the beginning of the test), and the only
impact to them would be a invocation of (often built-in) 'test'
utility, whose performance impact should be miniscule.

I'll wait for opinion from others, of course.

>
> [0] http://article.gmane.org/gmane.comp.version-control.git/277199
>
> -- >8 --
> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
> index e8d3c0f..d29cd7b 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -722,6 +722,8 @@ test_seq () {
>  # what went wrong.
>  
>  test_when_finished () {
> +	test "${BASH_SUBSHELL-0}" = 0 ||
> +	error "bug in test script: test_when_finished does nothing in a subshell"
>  	test_cleanup="{ $*
>  		} && (exit \"\$eval_ret\"); eval_ret=\$?; $test_cleanup"
>  }