Re: [PATCH 3/4] builtin/refs: add "update" subcommand

[Junio C Hamano <gitster@pobox.com>]

Patrick Steinhardt <ps@pks.im> writes:

> Add a new "update" subcommand which mirrors `git update-ref <refname>
> <oldoid> <newoid>`. This follows the same reasoning as the preceding
> commit.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  Documentation/git-refs.adoc |   7 ++
>  builtin/refs.c              |  50 +++++++++++++
>  t/meson.build               |   1 +
>  t/t1465-refs-update.sh      | 179 ++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 237 insertions(+)

I do not offhand know (and I am still away by 2 hours from the time
I wake up and start functioning) if update-ref shares the same
issue, but with "delete, update, rename" combo, lack of "create"
feels a bit annoying.  Wouldn't we want to offer an option to users
who want to ensure that the refs they create are truly new and they
are not overwriting a ref somebody has created?  Either (1) drop
"delete" and take a special value (e.g. "") as <newvalue> to signal
deletion and make the same special value used as <oldvalue> signals
creation, or (2) add "create" and insist that "update" takes only an
existing ref, would make the annoyance go away, I guess.

> +test_expect_success 'update creates a new reference' '
> +	test_when_finished "rm -rf repo" &&
> +	setup_repo repo &&
> +	(
> +		cd repo &&
> +		A=$(git rev-parse A) &&
> +		git refs update refs/heads/foo $A &&
> +		test_ref_matches refs/heads/foo "$A"
> +	)
> +'

Here we cannot test (and I strongly suspect that "git refs update"
and "git update-ref" lack ability to do so) a case where a creation
is attempted on an existing ref and fails.