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From: Jeff King <peff@peff.net>
To: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Cc: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v2 3/5] tests: turn GPG, GPGSM and RFC1991 into lazy prereqs
Date: Fri, 27 Mar 2020 05:10:04 -0400
Message-ID: <20200327091004.GA610157@coredump.intra.peff.net> (raw)
In-Reply-To: <nycvar.QRO.7.76.6.2003261450590.46@tvgsbejvaqbjf.bet>

On Thu, Mar 26, 2020 at 03:27:19PM +0100, Johannes Schindelin wrote:

> > OK. This looks good, even if I cannot help feel that my earlier patch
> > was perfectly sufficient. ;)
> 
> The mistake is all mine. I had totally missed that you turned GPG into a
> lazy prereq. So I had my patch finalized already before you pointed my
> nose at that fact.
> 
> Sorry about that.

No problem. And I hope my review didn't sound too passive-aggressive
with the "well, in MY version we did this...". I focused on the
differences because those were the parts that were new (and therefore
interesting) to me. But I don't think any of them are too important
either way.

> > I have a slight preference for "return 1" here. The "exit 1" works
> > because test_lazy_prereq puts us in an implicit subshell. But I think
> > this sets a bad example for people writing regular tests, where there is
> > no such subshell (and "return 1" is the only correct way to do it).
> 
> There are two reasons why I did not use `return` here:
> 
> - To me, prereq code is very distinct from writing tests. Just like we do
>   not &&-chain all the shell functions that live outside of tests, I don't
>   want to &&-chain all the prereq code.
> 
>   The point of the tests' commands is not to fail. The point of prereq's
>   code is to fail if the prereq is not met.

My only concern is whether people cargo-culting will notice the
distinction. But it's probably not a big deal.

> - Since this code is outside of a function, `return` felt like the wrong
>   semantic concept to me. And indeed, I see this (rather scary) part in
>   Bash's documentation of `return` (I did not even bother to look at the
>   POSIX semantics, it scared me so much):
> 
>       The return status is non-zero if `return` is supplied a non-numeric
>       argument, or is used outside a function and not during execution of
>       a script by `.` or `source`.
> 
>   So: the `1` is totally ignored in this context. That alone is reason
>   enough for me to completely avoid it, and use `exit` instead.

I agree the portability rules there are scary, but none of that applies
because we _are_ in a function: test_eval_inner_(). This behavior is
intentional and due to a7c58f280a (test: cope better with use of return
for errors, 2011-08-08). I thought we specifically advertised this
feature in t/README, but I can't seem to find it.

So my perspective was the opposite of yours: "return" is the officially
sanctioned way to exit early from a test snippet, and "exit" only
happens to work because of the undocumented fact that lazy prereqs
happen in a subshell. But it turns out neither was documented. :)

> > In mine I put the test_have_prereq outside the lazy prereq.
> 
> That makes it essentially a non-lazy prereq.
> 
> > I don't think it really matters either way (when we later ask if GPGSM
> > is set, there is no difference between nobody having defined it, and
> > having a lazy definition that said "no").
> 
> The difference is when running a test with `--run=<n>` where `<n>` refers
> to a test case that requires neither GPG nor GPGSM or RFC1991. My version
> will not evaluate the GPG prereq, yours still will.

Yes. Part of the reason I kept mine as it was is because it matched the
original behavior better (and I was really only using a lazy prereq
because we didn't have a non-lazy version). But there's really no reason
_not_ to be lazy, so as long as it isn't breaking anything I think
that's a better way forward. (And if it is breaking something, that
something should be fixed).

-Peff

  reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-23 13:09 [PATCH 0/2] Enable GPG in the Windows part of the CI/PR builds Johannes Schindelin via GitGitGadget
2020-03-23 13:09 ` [PATCH 1/2] tests(gpg): allow the gpg-agent to start on Windows Johannes Schindelin via GitGitGadget
2020-03-23 17:46   ` Junio C Hamano
2020-03-24 19:55     ` Johannes Schindelin
2020-03-24 20:59       ` Junio C Hamano
2020-03-24 22:26         ` Johannes Schindelin
2020-03-24 23:40           ` Junio C Hamano
2020-03-23 13:09 ` [PATCH 2/2] tests(gpg): increase verbosity to allow debugging Johannes Schindelin via GitGitGadget
2020-03-23 17:32   ` Jeff King
2020-03-23 18:04     ` Jeff King
2020-03-23 19:21       ` Junio C Hamano
2020-03-23 20:15         ` Jeff King
2020-03-23 21:28           ` Junio C Hamano
2020-03-23 21:31             ` Jeff King
2020-03-24 21:41               ` Johannes Schindelin
2020-03-24 22:05                 ` Jeff King
2020-03-24 22:25                   ` Johannes Schindelin
2020-03-24 22:33                     ` Jeff King
2020-03-25  5:41 ` [PATCH v2 0/5] Enable GPG in the Windows part of the CI/PR builds Johannes Schindelin via GitGitGadget
2020-03-25  5:41   ` [PATCH v2 1/5] tests(gpg): allow the gpg-agent to start on Windows Johannes Schindelin via GitGitGadget
2020-03-25  5:41   ` [PATCH v2 2/5] t/lib-gpg.sh: stop pretending to be a stand-alone script Johannes Schindelin via GitGitGadget
2020-03-26  8:21     ` Jeff King
2020-03-26 13:48       ` Johannes Schindelin
2020-03-26 19:31       ` Junio C Hamano
2020-03-25  5:41   ` [PATCH v2 3/5] tests: turn GPG, GPGSM and RFC1991 into lazy prereqs Johannes Schindelin via GitGitGadget
2020-03-25 17:25     ` Junio C Hamano
2020-03-26  8:35     ` Jeff King
2020-03-26 14:27       ` Johannes Schindelin
2020-03-27  9:10         ` Jeff King [this message]
2020-03-27 17:44           ` Junio C Hamano
2020-03-27 20:24             ` Eric Sunshine
2020-03-27 21:37               ` Junio C Hamano
2020-03-28 10:58                 ` Jeff King
2020-03-28 10:54             ` Jeff King
2020-03-28 23:49               ` [PATCH v2] t/README: suggest how to leave test early with failure Junio C Hamano
2020-03-29  7:23                 ` Eric Sunshine
2020-03-29 14:33                 ` Jeff King
2020-03-30 18:39           ` [PATCH v2 3/5] tests: turn GPG, GPGSM and RFC1991 into lazy prereqs Johannes Schindelin
2020-03-31  9:34             ` Jeff King
2020-03-25  5:41   ` [PATCH v2 4/5] tests: do not let lazy prereqs inside `test_expect_*` turn off tracing Johannes Schindelin via GitGitGadget
2020-03-25 17:23     ` Junio C Hamano
2020-03-26 13:45       ` Johannes Schindelin
2020-03-26  8:49     ` Jeff King
2020-03-26 14:34       ` Johannes Schindelin
2020-03-25  5:41   ` [PATCH v2 5/5] tests: increase the verbosity of the GPG-related prereqs Johannes Schindelin via GitGitGadget
2020-03-26  8:50     ` Jeff King
2020-03-26 14:36       ` Johannes Schindelin
2020-03-26 15:35   ` [PATCH v3 0/5] Enable GPG in the Windows part of the CI/PR builds Johannes Schindelin via GitGitGadget
2020-03-26 15:35     ` [PATCH v3 1/5] tests(gpg): allow the gpg-agent to start on Windows Johannes Schindelin via GitGitGadget
2020-03-26 15:35     ` [PATCH v3 2/5] t/lib-gpg.sh: stop pretending to be a stand-alone script Johannes Schindelin via GitGitGadget
2020-03-26 15:35     ` [PATCH v3 3/5] tests: do not let lazy prereqs inside `test_expect_*` turn off tracing Johannes Schindelin via GitGitGadget
2020-03-26 15:35     ` [PATCH v3 4/5] tests: turn GPG, GPGSM and RFC1991 into lazy prereqs Johannes Schindelin via GitGitGadget
2020-03-26 15:35     ` [PATCH v3 5/5] tests: increase the verbosity of the GPG-related prereqs Johannes Schindelin via GitGitGadget
2020-03-27  9:12     ` [PATCH v3 0/5] Enable GPG in the Windows part of the CI/PR builds Jeff King
2020-03-27 17:45       ` Junio C Hamano

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