Re: [PATCH v3 3/3] test-lib: make BAIL_OUT() work in tests and prereq

From: Fabian Stelzer <fs@gigacodes.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	git@vger.kernel.org, "Adam Dinwoodie" <adam@dinwoodie.org>,
	"Jeff King" <peff@peff.net>
Subject: Re: [PATCH v3 3/3] test-lib: make BAIL_OUT() work in tests and prereq
Date: Tue, 30 Nov 2021 15:38:21 +0100	[thread overview]
Message-ID: <20211130143821.7dz5jj2z2x2q2ytn@fs> (raw)
In-Reply-To: <xmqqo8634zrz.fsf@gitster.g>

On 28.11.2021 15:38, Junio C Hamano wrote:
>Fabian Stelzer <fs@gigacodes.de> writes:
>
>>>I was expecting something along the lines of ...
>>>
>>># What is written by tests to their FD #1 and #2 are sent to
>>># different places depending on the test mode (e.g. /dev/null in
>>># non-verbose mode, piped to tee with --tee option, etc.)  Original
>>># FD #1 and #2 are saved away to #5 and #7, so that test framework
>>># can use them to send the output to these low FDs before the
>>># mode-specific redirection.
>>>
>>>... but this only talks about the output side.  The final version
>>>needs to mention the input side, too.
>>>
>>
>> I like to use the term stdin/err/out since that is what i would grep for
>> when trying to find out more about the test i/o behaviour.
>
>I do not mind phrasing "original FD #1" as "original standard
>output" at all.  I just wanted to make sure it is clear to readers
>whose FD #1 and FD #5 we are talking about. In other words, the
>readers should get a clear understanding of where they are writing
>to, when the code they write in test_expect_success block outputs to
>FD #1, and what the code needs to do if it wants to always show
>something to the original standard output stream.

The current version in my branch is now:

What is written by tests to stdout and stderr is sent so different places
depending on the test mode (e.g. /dev/null in non-verbose mode, piped to tee
with --tee option, etc.). We save the original stdin to FD #6 and stdout and
stderr to #5 and #7, so that the test framework can use them (e.g. for
printing errors within the test framework) independently of the test mode.

which I think should make this sufficiently clear.
I'm wondering now though if we should write to #7 instead of #5 in 
BAIL_OUT(). The current use in test-lib/test-lib-functions seems a bit 
inconsistent.

For example:
error >&7 "bug in the test script: $*"
echo >&7 "test_must_fail: only 'git' is allowed: $*"

but:
echo >&5 "FATAL: Cannot prepare test area"
echo >&5 "FATAL: Unexpected exit with code $code"

Sometimes these errors result in immediate exit 1, but not always.

I'm not sure if the TAP framework that BAIL_OUT() references expects the 
bail out error on a specific fd.