Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> writes:
> On Tue, Jul 20, 2010 at 18:00, Junio C Hamano <gitster@xxxxxxxxx> wrote:
>
>> Run a git command and ensure it fails in a controlled way. Use
>> this instead of "! <git-command>". When git-command dies due to a
>> segfault, test_must_fail diagnoses it as an error; "! <git-command>"
>> treats it as just another expected failure. letting such a bug go
>> unnoticed.
>
> To add to that:
>
> Don't use test_must_fail to negate the return values of commands
> on the system like grep, sed etc. If we can't trust that the core
> utilities won't randomly segfault we might as well die horribly.
I think you are being incoherent. If we can't trust system "grep" and it
randomly segfaults, then a test:
git some-command >actual &&
! grep string-that-should-not-be-in-the-output actual
would _pass_ when the command segfaults. I do agree with you that "We
might as well die horribly", and the way you do so is by protecting the
test with test_must_fail, like this:
git some-command >actual &&
test_must_fail grep string-that-should-not-be-in-the-output actual
Having said that, as we _do_ trust system tools to a certain degree, we do
not care very deeply about this. IOW, I wouldn't want to see a patch that
rewrites "! grep" to "test_must_fail grep".
Thanks.
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