Re: [PATCH v6] Implement --first-parent for git rev-list --bisect

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

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:

> Hi Tiago,
>
> On Tue, 28 Aug 2018, Tiago Botelho wrote:
>
>> This will enable users to implement bisecting on first parents
>> which can be useful for when the commits from a feature branch
>> that we want to merge are not always tested.
>
> This message is still lacking the explanation I asked for, namely for the
> lines:
>
> 	@@ -329,6 +334,11 @@ static struct commit_list *do_find_bisection(struct commit_list *list,
> 	 	if (0 <= weight(p))
> 	 		continue;
> 	 	for (q = p->item->parents; q; q = q->next) {
> 	+		if ((bisect_flags & BISECT_FIRST_PARENT)) {
> 	+			if (weight(q) < 0)
> 	+				q = NULL;
> 	+			break;
> 	+		}
> 	 	if (q->item->object.flags & UNINTERESTING)
> 	 		continue;
> 	 	if (0 <= weight(q))

I've just finished scanning the discussion thread on public-inbox
for v5, v4, v3, v2 and the initial round of this series, but found
your comments only on the tests.  If you have a pointer that would
be great; it also is OK to say what kind of explanation is needed
for that addition again.  

FWIW I too was puzzled about the correctness of the added logic
above, especially the part that reads weight(q) before checking if
it is not UNINTERESTING, but I covered it on a separate message.

> I would have preferred to reuse the already existing commits generated in
> the `setup` phase rather than generating yet another batch, and to not
> introduce an inconsistent way to present a commit graph (compare your
> diagram with the one in
> https://github.com/git/git/blob/v2.18.0/t/t6002-rev-list-bisect.sh#L64-L90
> i.e. *in the same file*)

As I already said in the previous round, I do agree with these.
That is, ...

>> diff --git a/t/t6002-rev-list-bisect.sh b/t/t6002-rev-list-bisect.sh
>> index a66140803..1bc297de5 100755
>> --- a/t/t6002-rev-list-bisect.sh
>> +++ b/t/t6002-rev-list-bisect.sh
>> @@ -263,4 +263,62 @@ test_expect_success 'rev-parse --bisect can default to good/bad refs' '
>>  	test_cmp expect.sorted actual.sorted
>>  '
>>  
>> +# We generate the following commit graph:
>> +#
>> +#   B ------ C
>> +#  /          \
>> +# A            FX
>> +#  \          /
>> +#   D - CC - EX
>> +
>> +test_expect_success 'setup' '
>> +  test_commit A &&
>> +  test_commit B &&
>> +  test_commit C &&
>> +  git reset --hard A &&
>> +  test_commit D &&
>> +  test_commit CC &&
>> +  test_commit EX &&
>> +  test_merge FX C
>> +'

... the above graph construction should not be necessary.  An
earlier part of t6002 would have already created a history of
suitable shape to use for writing the following tests.

>> +test_output_expect_success "--bisect --first-parent" 'git rev-list --bisect --first-parent FX ^A' <<EOF
>> +$(git rev-parse CC)
>> +EOF
>> +
>> +test_output_expect_success "--first-parent" 'git rev-list --first-parent FX ^A' <<EOF
>> +$(git rev-parse FX)
>> +$(git rev-parse EX)
>> +$(git rev-parse CC)
>> +$(git rev-parse D)
>> +EOF
>> +
>> +test_output_expect_success "--bisect-vars --first-parent" 'git rev-list --bisect-vars --first-parent FX ^A' <<EOF
>> +bisect_rev='$(git rev-parse CC)'
>> +bisect_nr=1
>> +bisect_good=1
>> +bisect_bad=1
>> +bisect_all=4
>> +bisect_steps=1
>> +EOF
>> +
>> +test_expect_success "--bisect-all --first-parent" '
>> +cat >expect <<EOF &&
>> +$(git rev-parse CC) (dist=2)
>> +$(git rev-parse EX) (dist=1)
>> +$(git rev-parse D) (dist=1)
>> +$(git rev-parse FX) (dist=0)
>> +EOF
>> +
>> +# Make sure we have the same entries, nothing more, nothing less
>> +git rev-list --bisect-all --first-parent FX ^A >actual &&
>> +  sort actual >actual.sorted &&
>> +  sort expect >expect.sorted &&
>> +  test_cmp expect.sorted actual.sorted &&
>> +  # Make sure the entries are sorted in the dist order
>> +  sed -e "s/.*(dist=\([1-9]*[0-9]\)).*/\1/" actual >actual.dists &&
>> +  sort -r actual.dists >actual.dists.sorted &&
>> +  test_cmp actual.dists.sorted actual.dists
>> +'
>> +
>>  test_done
>> -- 
>> 2.16.3
>> 
>>