Re: [PATCH v3] commit-tree: add missing --gpg-sign flag

["Martin Ågren" <martin.agren@gmail.com>]

Hi Brandon,

Thanks for a v3.

On Sat, 19 Jan 2019 at 04:36, Brandon Richardson <brandon1024.br@gmail.com> wrote:
> -		if (skip_prefix(arg, "-S", &sign_commit))
> +		if(!strcmp(arg, "--gpg-sign")) {

(Same nit as Junio about the missing space after "if".)

> +			sign_commit = "";

Nice. ;-)

> +			continue;
> +		}

>	# commit.gpgsign is still on but this must not be signed
>	git tag ninth-unsigned $(echo 9 | git commit-tree HEAD^{tree}) &&
>	# explicit -S of course must sign.
> -	git tag tenth-signed $(echo 9 | git commit-tree -S HEAD^{tree})
> +	git tag tenth-signed $(echo 10 | git commit-tree -S HEAD^{tree}) &&
> +
> +	# --gpg-sign[=<key-id>] must sign.
> +	echo 11 >file && test_tick && git commit -S -a -m "eleventh signed" &&
> +	git tag eleventh-signed &&
> +	git commit-tree --gpg-sign -m "twelfth signed" HEAD^{tree} &&
> +	git tag twelfth-signed &&
> +    git commit-tree --gpg-sign=B7227189 -m "thirteenth signed" HEAD^{tree} &&
> +    git tag thirteenth-signed
>  '

(These last two lines are not tab-indented, but indented by four spaces.
They were perhaps mangled by some copy-pasting.)

Running this test, we end up with three tags on one commit:
eleventh-signed, twelfth-signed and thirteenth-signed. So as long as
`git commit -S` works when we use the number 11, everything will pass,
and we won't really test what we wanted to test. We will verify that
`git commit-tree` doesn't choke on "--gpg-sign[=foo]", but we won't
verify that it handles it correctly.

(Just recently, it was pointed out on this list that `git log --count`
won't complain about "--count", but won't act on it, either. So such
errors are not unheard of.)

I looked into this test in a bit more detail, and it seems to be quite
hard to get right. Part of the reason is that `git commit-tree` requires
a bit more careful use than `git commit`, but part of it is that the
tests that we already have for `git commit-tree [-S]` right before the
ones you're adding are a bit too loose, IMHO. So they're not ideal for
copy-pasting... I've come up with the patch below, which you might want
to use as a basis for your work.

That is, you could `git am --scissors` this patch on a fresh branch and
`git commit --amend --signoff --no-edit` it (see
Documentation/SubmittingPatches, "forwarding somebody else's patch"),
then base your work on it, e.g., by cherry-picking your v3 commit.

I think you would want to add 2x3 lines of tests (3 for `--gpg-sign`, 3
for `--gpg-sign=...`). That would give you eleventh-signed and
twelfth-signed and you wouldn't need any invocation of `git commit` (so
no thirteenth-signed).

If you're not up for that, just let me know and I could instead rebase
your patch on top of mine and submit both as a v4. I think this has come
along nicely, and now it's really just about having a robust test.

Martin

-- >8 --
Subject: [PATCH] t7510: invoke git as part of &&-chain

If `git commit-tree HEAD^{tree}` fails on us and produces no output on
stdout, we will substitute that empty string and execute `git tag
ninth-unsigned`, i.e., we will tag HEAD rather than a newly created
object. But we are lucky: we have a signature on HEAD, so we should
eventually fail the next test, where we verify that "ninth-unsigned" is
indeed unsigned.

We have a similar problem a few lines later. If `git commit-tree -S`
fails with no output, we will happily tag HEAD as "tenth-signed". Here,
we are not so lucky. The tag ends up on the same commit as
"eighth-signed-alt", and that's a signed commit, so t7510-signed-commit
will pass, despite `git commit-tree -S` failing.

Make these `git commit-tree` invocations a direct part of the &&-chain,
so that we can rely less on luck and set a better example for future
tests modeled after this one. Fix a 9/10 copy/paste error while at it.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
 t/t7510-signed-commit.sh | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/t/t7510-signed-commit.sh b/t/t7510-signed-commit.sh
index 86d3f93fa2..58f528b98f 100755
--- a/t/t7510-signed-commit.sh
+++ b/t/t7510-signed-commit.sh
@@ -49,9 +49,13 @@ test_expect_success GPG 'create signed commits' '
 	git tag eighth-signed-alt &&
 
 	# commit.gpgsign is still on but this must not be signed
-	git tag ninth-unsigned $(echo 9 | git commit-tree HEAD^{tree}) &&
+	echo 9 | git commit-tree HEAD^{tree} >oid &&
+	test_line_count = 1 oid &&
+	git tag ninth-unsigned $(cat oid) &&
 	# explicit -S of course must sign.
-	git tag tenth-signed $(echo 9 | git commit-tree -S HEAD^{tree})
+	echo 10 | git commit-tree -S HEAD^{tree} >oid &&
+	test_line_count = 1 oid &&
+	git tag tenth-signed $(cat oid)
 '
 
 test_expect_success GPG 'verify and show signatures' '
-- 
2.20.1.98.gecbdaf0899