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From: Amanda Shafack <shafack.likhene@gmail.com>
To: Eric Sunshine <sunshine@sunshineco.com>
Cc: Amanda Shafack via GitGitGadget <gitgitgadget@gmail.com>,
	Git List <git@vger.kernel.org>,
	Emily Shaffer <emilyshaffer@google.com>,
	Jonathan Nieder <jrnieder@gmail.com>
Subject: Re: [PATCH 1/2] t9832,t2200: avoid using pipes in git commands
Date: Sun, 18 Oct 2020 14:57:51 +0100
Message-ID: <CAGxm6oWT=LG7KczvKaa5ta=LBAkFsHHYsCXLB7tBfn==Z0g9DQ@mail.gmail.com> (raw)
In-Reply-To: <CAPig+cQnfcc9W3qE5XkyLiwNyK8Wm2SsAyjzatDWEVUi3s8APw@mail.gmail.com>

Thanks for your feedback, I now have a better understanding. I have
made the changes you requested.


On Sun, Oct 18, 2020 at 7:11 AM Eric Sunshine <sunshine@sunshineco.com> wrote:
>
> On Sat, Oct 17, 2020 at 12:02 PM Amanda Shafack via GitGitGadget
> <gitgitgadget@gmail.com> wrote:
> > When the upstream of a pipe throws an error, the downstream still
> > executes normally. This happens because the exit code of the upstream
> > in a pipe is ignored. This behavior can make debugging very hard
> > incase a test fails.
>
> To be more precise, we're not worried about difficulty of debugging
> when a Git command is upstream in a pipe. What we are more concerned
> with is that an unexpected failure of the Git command will go
> unnoticed (unless it also happens to produce wrong output which is
> later caught somewhere downstream). By avoiding placing Git upstream
> in a pipe, we can actively catch a failure of the Git command. The
> commit message should focus on that reason instead.
>
> > Also, pipes are prone to deadlocks. If the
> > upstream gets full, the commands downstream will never start.
>
> I don't think this is ever an issue in Git tests, so talking about it
> here probably only muddies the waters, thus makes the commit message
> less precise and more hand-wavy. Dropping this sentence is
> recommended.
>
> > Commit c6f44e1da5 (t9813: avoid using pipes, 2017-01-04) noticed that
> > the exit code of upstream in the pipe is ignored, thus using pipes
> > should be avoided.
>
> There are a lot of commits in the project history which perform this
> sort of transformation, so it's not clear to the reader why this
> particular commit is called out as being important. If it's not, then
> I'd recommend dropping this sentence, as well.
>
> > diff --git a/t/t2200-add-update.sh b/t/t2200-add-update.sh
> >  test_expect_success '"add -u non-existent" should fail' '
> >         test_must_fail git add -u non-existent &&
> > -       ! (git ls-files | grep "non-existent")
> > +       ! (
> > +               git ls-files >actual &&
> > +               grep "non-existent" actual
> > +       )
> >  '
>
> This transformation appears to be incorrect. See my review of patch
> [2/2] for details.
>
> > diff --git a/t/t9832-unshelve.sh b/t/t9832-unshelve.sh
> > @@ -68,7 +68,8 @@ EOF
> > -               git show refs/remotes/p4-unshelved/$change | grep -q "Further description" &&
> > +               git show refs/remotes/p4-unshelved/$change >actual &&
> > +               grep -q "Further description" actual &&
>
> This transformation looks fine.



-- 

Cheers!

Amanda  Shafack

  reply	other threads:[~2020-10-18 13:59 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-17 16:02 [PATCH 0/2] [Outreachy][Patch v1] t9832,t2200: avoid using pipes in git related commands Amanda  Shafack  via GitGitGadget
2020-10-17 16:02 ` [PATCH 1/2] t9832,t2200: avoid using pipes in git commands Amanda Shafack via GitGitGadget
2020-10-18  6:11   ` Eric Sunshine
2020-10-18 13:57     ` Amanda Shafack [this message]
2020-10-17 16:02 ` [PATCH 2/2] t2200: modify code syntax Amanda  Shafack via GitGitGadget
2020-10-18  5:55   ` Eric Sunshine
2020-10-18 13:59     ` Amanda Shafack
2020-10-18 14:42 ` [PATCH v2] t9832,t2200: avoid using pipes in git commands Amanda  Shafack  via GitGitGadget
2020-10-18 19:25   ` Eric Sunshine
2020-10-18 20:04     ` Junio C Hamano
2020-10-18 22:04       ` Amanda Shafack
2020-10-18 20:40     ` Amanda Shafack
2020-10-18 20:48   ` [PATCH v3] t2200,t9832: avoid using 'git' upstream in a pipe Amanda  Shafack  via GitGitGadget
2020-10-18 21:01     ` Junio C Hamano

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