From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Side effects in Git's test suite, was Re: [PATCH] revert: optionally refer to commit in the "reference" format
Date: Mon, 30 May 2022 18:50:58 +0200 (CEST) [thread overview]
Message-ID: <nycvar.QRO.7.76.6.2205301840410.349@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <xmqq35gzn9vk.fsf@gitster.g>
Hi Junio,
On Mon, 23 May 2022, Junio C Hamano wrote:
> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
> >> +test_expect_success 'identification of reverted commit (reference)' '
> >> + git checkout --detach to-ident &&
> >> + git revert --reference --no-edit HEAD &&
> >> + git cat-file commit HEAD >actual.raw &&
> >> + grep "^This reverts " actual.raw >actual &&
> >> + echo "This reverts commit $(git show -s --pretty=reference HEAD^)." >expect &&
> >> + test_cmp expect actual
> >> +'
> >
> > If it was up to me, I would combine these three test cases, if only to
> > help the `--run=<single-number>` case (the latter two depend on the
> > side effect of the first one to create a `to-ident` tag).
>
> I wonder if our prereq infrastructure is lightweight and scalable enough
> so that we can easily add a support a pseudo-prerequisite PREVIOUS that
> lets us say
>
> test_expect_success PREVIOUS "identification ..." '
> ...
> '
>
> to mean that this test requires the previous test has not been
> skipped.
In theory, this sounds good to me.
In practice, however, side effects are awful and make everything harder,
from developing code to debugging to helping new contributors. I wish we
would do away with them altogether and have something more akin to the
before/after constructs known from e.g. TestNG (think `@BeforeTest` and
`@BeforeClass`).
One option would be to mark `setup` steps completely differently, sort of
imitating the prereq infrastructure instead of using
`test_expect_success`. Kind of prereqs, but required to pass.
This could potentially allow us to randomize the order in which the test
cases are run, to identify and fix (unintended) side effects.
A complication is that we have nothing in the way of `@AfterClass`, i.e.
we do not have a way to, say, run an Apache instance for the lifecycle of
a given test script _and tear it down at the end_.
Another, rather obvious complication is that we have 17 years of commit
history introducing side effects left and right :laughing:
Ciao,
Dscho
next prev parent reply other threads:[~2022-05-30 16:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-22 4:32 [PATCH] revert: optionally refer to commit in the "reference" format Junio C Hamano
2022-05-23 13:25 ` Johannes Schindelin
2022-05-23 22:48 ` Junio C Hamano
2022-05-27 6:01 ` [PATCH v3] " Junio C Hamano
2022-05-30 16:40 ` Johannes Schindelin
2022-05-31 14:00 ` Phillip Wood
2022-06-01 4:45 ` Junio C Hamano
2022-06-01 15:03 ` Phillip Wood
2022-06-01 15:14 ` Ævar Arnfjörð Bjarmason
2022-06-01 21:52 ` Junio C Hamano
2022-05-30 16:50 ` Johannes Schindelin [this message]
2022-05-31 8:03 ` Side effects in Git's test suite, was Re: [PATCH] " Ævar Arnfjörð Bjarmason
2022-05-23 13:45 ` Ævar Arnfjörð Bjarmason
2022-05-23 22:37 ` Junio C Hamano
2022-05-24 8:12 ` Ævar Arnfjörð Bjarmason
2022-05-24 19:11 ` Junio C Hamano
2022-05-26 11:17 ` Phillip Wood
2022-05-26 17:29 ` Junio C Hamano
2022-06-26 9:29 ` René Scharfe
2022-06-27 15:38 ` Junio C Hamano
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