Re: [Outreachy][PATCH v2] t6050: avoid pipes with downstream Git commands

[Chizoba ODINAKA <chizobajames21@gmail.com>]

Hi Philip,
On Thu, 10 Oct 2024 at 15:08, Phillip Wood <phillip.wood123@gmail.com> wrote:
>
> Hi Chizoba
>
> On 10/10/2024 07:39, chizobajames21@gmail.com wrote:
> > From: Chizoba ODINAKA <chizobajames21@gmail.com>
> >
> > In pipes, the exit code of a chain of commands is determined by
> > the downstream command.
>
> I would perhaps say "final command" rather than "downstream command" as
> in a pipeline "cmd1 | cmd2 | cmd3" cmd2 and cmd3 are downstream of cmd1
> but it is the exit code of cmd3 that will be used
>
Yes, final command is a more appropriate explain.
> > In order not to loss the entire result code of tests,
> > write output of upstreams into a file.
>
> We're interested in checking the exit code of git, but not other
> commands so it would be helpful to make that clear. Usman's patch [1]
> has a good explanation of this.
>
I just read that sentence again, it obviously needs some clarity. "In order not
to miss the exit code of any Git command, avoid using pipe and write
output into a file"
has more clarity. I will look up on Usman's patch [1], before my next changes.

> This patch also changes instances of "grep" to "test_grep" so the commit
> message needs to explain the reason for that change which is that it
> gives a better debugging experience if the test fails.
>
I had included that in my "Changes in v2", appended beneath my "Sign-off-by".
"Changes in v2:
- split multiple commands chain on the same line across multiple line,
  for easier readability
- replace "grep" with "test_grep", for more context in case of a "grep"
  failure"
Maybe it was not so obvious that you didn't notice, or it is not the
traditional way of including it.

> The patch is looking pretty good, most of the conversions look correct.
> I've left a few comments below
>
>
> [1]
> https://lore.kernel.org/git/bfff7937cd20737bb5a8791dc7492700b1d7881f.1728315124.git.gitgitgadget@gmail.com
>
> >   test_expect_success 'replace the author' '
> > -     git cat-file commit $HASH2 | grep "author A U Thor" &&
> > -     R=$(git cat-file commit $HASH2 | sed -e "s/A U/O/" | git hash-object -t commit --stdin -w) &&
> > -     git cat-file commit $R | grep "author O Thor" &&
> > +     git cat-file commit $HASH2 >actual &&
> > +     test_grep "author A U Thor" actual &&
> > +     git cat-file commit $HASH2 >actual &&
>
> You don't need to repeat this command now that we are saving the output
> of "git cat-file commit $HASH2"
>
> > +     R=$(sed -e "s/A U/O/" actual | git hash-object -t commit --stdin -w) &&
> > +     git cat-file commit $R >actual &&
> > +     test_grep "author O Thor" actual &&
>
> >   test_expect_success 'push branch with replacement' '
> > -     git cat-file commit $PARA3 | grep "author A U Thor" &&
> > -     S=$(git cat-file commit $PARA3 | sed -e "s/A U/O/" | git hash-object -t commit --stdin -w) &&
> > -     git cat-file commit $S | grep "author O Thor" &&
> > +     git cat-file commit $PARA3 >actual &&
> > +     test_grep "author A U Thor" actual &&
> > +     git cat-file commit $PARA3 >actual &&
>
> We can drop this line for the same reason as above
>
> > +     S=$(sed -e "s/A U/O/" actual | git hash-object -t commit --stdin -w) &&
> > +     git cat-file commit $S >actual &&
> > +     test_grep "author O Thor" actual &&
>
> > @@ -260,14 +291,14 @@ test_expect_success 'fetch branch with replacement' '
> >               cd clone_dir &&
> >               git fetch origin refs/heads/tofetch:refs/heads/parallel3 &&
> >               git log --pretty=oneline parallel3 >output.txt &&
> > -             ! grep $PARA3 output.txt &&
> > +             ! test_grep $PARA3 output.txt &&
>
> test_grep will print an error message the pattern does not match. In
> this case we expect it not to match so we want to print an error if it
> does match. We can do that with
>
>         test_grep ! $PARA3 output.txt &&
>
> >   test_expect_success 'index-pack and replacements' '
> > -     git --no-replace-objects rev-list --objects HEAD |
> > +     git --no-replace-objects rev-list --objects HEAD >actual &&
> >       git --no-replace-objects pack-objects test- &&
>
> This command has lost its input - you need to use '<actual' to get it to
> read output from "git rev-list". This test itself could probably do a
> better job of checking that index-pack does what we expect but that is
> outside the scope of this patch.
>
> >       git index-pack test-*.pack
> >   '
>
> Everything that I've not commented on looks correct to me.
>
Thanks Philip for the review, I will make the needed changes in my
next patch. And look into
the index-pack proposal in a new patch, since it is outside this scope.
> Best Wishes
>
> Phillip

Thanks
Chizoba