From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Date: Tue, 20 Jul 2010 17:52:42 GMT
Subject: Re: [PATCH] t/t3700: convert two uses of negation operator '!' to use test_must_fail
Message-ID: <AANLkTilpspywp68veHtYbtfZytHr_0IThksmtkGAjWRg@mail.gmail.com>
In-Reply-To: <20100720163822.GA8492@localhost.localdomain>

On Tue, Jul 20, 2010 at 16:38, Jared Hance <jaredhance@gmail.com> wrote:
> On Tue, Jul 20, 2010 at 11:32:33AM -0500, Brandon Casey wrote:
>> I think you have misunderstood the explanation of test_must_fail.  The
>> paragraph you quoted actually recommends using test_must_fail instead
>> of "! <git-command>".
>>
>> It says:
>>
>>    Use this instead of "! <git-command>" to fail when git commands
>>    segfault.
>>
>> Or with a slight rewording:
>>
>>    Use test_must_fail instead of "! <git-command>" since test_must_fail
>>    will fail when <git-command> segfaults.
>
> I think the wording of description of test_must_fail is slightly
> ambiguous. I read it to mean that:
>
>    Use test_must_fail only when you are testing to see if git will
>    segfault.

I've interpreted it to mean that as well, but it's starting to look
like a good example of a garden path sentence.

Anyway, it looks like we're wrong and Brandon was right. But I'm going
to submit a doc patch to t/README. Here's the existing use of !
v.s. test_must_fail:

    $ cat *.sh | grep -c 'test_must_fail git'
    863
    $ cat *sh | grep -c '! git '
    30

I.e. ! is only used to negate non-git commands like test.

The example in the comments for test_must_fail in test-lib.sh backs this up:

    # Writing this as "! git checkout ../outerspace" is wrong, because
    # the failure could be due to a segv.  We want a controlled failure.

> Rather than:
>
>    Use test_must_fail to be safe from git segfaults.