Re: [PATCH v2 1/3] stash: add test to ensure reflog --rewrite --updatref behavior

[John Cai <johncai86@gmail.com>]

Hi Junio,

On 23 Feb 2022, at 17:51, Junio C Hamano wrote:

> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>
>>> +test_expect_success 'drop stash reflog updates refs/stash' '
>>> +	git reset --hard &&
>>> +	git rev-parse refs/stash >expect &&
>>> +	echo 9 >file &&
>>> +	git stash &&
>>> +	git stash drop stash@{0} &&
>>> +	git rev-parse refs/stash >actual &&
>>> +	test_cmp expect actual
>>> +'
>>
>> This one will be portable to the reftable backend.
>>
>>> +test_expect_success 'drop stash reflog updates refs/stash with rewrite' '
>>
>> But as I noted in <220222.86fsob88h7.gmgdl@evledraar.gmail.com> (but it
>> was easy to miss) this test will need to depend on REFFILES. So just
>> changing this line to:
>>
>>     test_expect_success REFFILES 'drop stash[...]'
>>
>>> +	git reset --hard &&
>>> +	echo 9 >file &&
>>> +	git stash &&
>>> +	oid="$(git rev-parse stash@{0})" &&
>>> +	git stash drop stash@{1} &&
>>> +	cut -d" " -f1-2 .git/logs/refs/stash >actual &&
>>> +	cat >expect <<-EOF &&
>>> +	$(test_oid zero) $oid
>>> +	EOF
>>> +	test_cmp expect actual
>>> +'
>
> Why should this be tested with "cut" in the first place, though?
>
> If we start from
>
>     stash@{0} = A
>     stash@{1} = B
>     stash@{2} = C
>
> and after saying "drop stash@{1}", what we need to check is that
>
>     stash@{0} = A
>     stash@{1} = C

Yes, this is true but that doesn't seem to test the --rewrite functionality.
I could be missing something, but it seems that the reflog --rewrite option
will write the LHS old oid value in the .git/logs/refs/stash file. When
--rewrite isn't used, the reflog delete still does the right thing to the
RHS entry.

I couldn't find any way to check this LFS value other than reaching into the
actual file. If there is a way that would be preferable.
>
> now holds, which can be done with "git rev-parse", and the fact that
> the ref-files backend happens to record both before-and-after object
> IDs is an irrelevant implementation detail, no?
>
> I am still puzzled.