Re: [PATCH] don't use test_must_fail with grep

[Luke Diamand <luke@diamand.org>]

On 1 January 2017 at 14:50, Johannes Sixt <j6t@kdbg.org> wrote:
> Am 01.01.2017 um 15:23 schrieb Luke Diamand:
>>
>> On 31 December 2016 at 11:44, Pranit Bauva <pranit.bauva@gmail.com> wrote:
>>>
>>> diff --git a/t/t9813-git-p4-preserve-users.sh
>>> b/t/t9813-git-p4-preserve-users.sh
>>> index 0fe231280..2384535a7 100755
>>> --- a/t/t9813-git-p4-preserve-users.sh
>>> +++ b/t/t9813-git-p4-preserve-users.sh
>>> @@ -126,13 +126,13 @@ test_expect_success 'not preserving user with mixed
>>> authorship' '
>>>                 grep "git author charlie@example.com does not match" &&
>>>
>>>                 make_change_by_user usernamefile3 alice alice@example.com
>>> &&
>>> -               git p4 commit |\
>>> -               test_must_fail grep "git author.*does not match" &&
>>> +               ! git p4 commit |\
>>> +               grep "git author.*does not match" &&
>>
>>
>> Would it be clearer to use this?
>>
>>     git p4 commit |\
>>     grep -q -v "git author.*does not match" &&
>>
>> With your original change, I think that if "git p4 commit" fails, then
>> that expression will be treated as a pass.
>
>
> No. The exit code of the upstream in a pipe is ignored. For this reason,
> having a git invocation as the upstream of a pipe *anywhere* in the test
> suite is frowned upon. Hence, a better rewrite would be
>
>         git p4 commit >actual &&
>         ! grep "git author.*does not match" actual &&
>
> which makes me wonder: Is the message that we do expect not to occur
> actually printed on stdout? It sounds much more like an error message, i.e.,
> text that is printed on stderr. Wouldn't we need this?
>
>         git p4 commit >actual 2>&1 &&
>         ! grep "git author.*does not match" actual &&

The message is actually part of a template presented to the user via
their chosen editor. For this test, we set the editor to be "cat", so
it comes out on stdout.

Your first suggestion would therefore be fine (and similarly for the
other cases).