Re: [PATCH v2 2/2] test-lib: introduce required prereq for test runs

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Fri, Nov 19 2021, Fabian Stelzer wrote:

> On 19.11.2021 12:13, Ævar Arnfjörð Bjarmason wrote:
>>
>>On Wed, Nov 17 2021, Fabian Stelzer wrote:
>>
>>> In certain environments or for specific test scenarios we might expect a
>>> specific prerequisite check to succeed. Therefore we would like to
>>> trigger an error when running our tests if this is not the case.
>>
>>trigger an error but...
>>
>>> To remedy this we add the environment variable GIT_TEST_REQUIRE_PREREQ
>>> which can be set to a comma separated list of prereqs. If one of these
>>> prereq tests fail then the whole test run will abort.
>>
>>..here it's "abort the whole test run". If that's what you want use
>>BAIL_OUT, not error. See: 234383cd401 (test-lib.sh: use "Bail out!"
>>syntax on bad SANITIZE=leak use, 2021-10-14)
>>
>
> Hm, while testing this change i noticed another problem that i really
> have no idea how to fix.
> When a test uses test_have_prereq then the error/BAIL_OUT message will only be printed
> when run with '-v'. This is not the case when the prereq is specified
> in the test header. The test run will abort, but no error will be
> printed which can be quite confusing :/
> I guess this has something to do with how tests are run in subshells and
> their outputs only printed with -v. Maybe there should be some kind of
> override for BAIL_OUT at least? Not sure if/how this could be done.

It has to do with how we juggle file descriptors around, see test_eval_
in test-lib.sh.

So the "real" stdout is fd 5, not 1 when you're in a prereq.

Just:

    BAIL_OUT "bad" >&5

Will work, maybe it's a good idea to have:

	BAIL_OUT_PREREQ () {
		BAIL_OUT $@ >&5
	}

Sorry, I forgot about that caveat when suggesting it.