Subject: Re: [RFC PATCH 3/7] rebase -i: Stop on root commits with empty log messages

From: Fabian Ruch <[email-masked]>
Date: Sun, 22 Jun 2014 02:32:14 +0200

Hi Eric,

On 06/21/2014 02:33 AM, Eric Sunshine wrote:
> On Wed, Jun 18, 2014 at 11:28 PM, Fabian Ruch <[email-masked]> wrote:
>> When `rebase` is executed with `--root` but no `--onto` is specified,
>> `rebase` creates a sentinel commit which is replaced with the root
>> commit in three steps. This combination of options results never in a
>> fast-forward.
>>
>>  1. The sentinel commit is forced into the authorship of the root
>>     commit.
>>
>>  2. The changes introduced by the root commit are applied to the index
>>     but not committed. If this step fails for whatever reason, all
>>     commit information will be there and the user can safely run
>>     `git-commit --amend` after resolving the problems.
>>
>>  3. The new root commit is created by squashing the changes into the
>>     sentinel commit which already carries the authorship of the
>>     cherry-picked root commit.
>>
>> The command line used to create the commit in the third step specifies
>> effectless and erroneous options. Remove those.
>>
>>  - `--allow-empty-message` is erroneous: If the root's commit message is
>>    empty, the rebase shall fail like for any other commit that is on the
>>    to-do list and has an empty commit message.
>>
>>    Fix the bug that git-rebase does not fail when the initial commit has
>>    an empty log message but is replayed using `--root` is specified.
>>    Add test.
>>
>>  - `-C` is effectless: The commit being amended, which is the sentinel
>>    commit, already carries the authorship and log message of the
>>    cherry-picked root commit. The committer email and commit date fields
>>    are reset either way.
>>
>> After all, if step two fails, `rebase --continue` won't include these
>> flags in the git-commit command line either.
>>
>> Signed-off-by: Fabian Ruch <[email-masked]>
>> ---
>>  git-rebase--interactive.sh |  4 ++--
>>  t/t3412-rebase-root.sh     | 39 +++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 41 insertions(+), 2 deletions(-)
>>
>> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
>> index fffdfa5..f09eeae 100644
>> --- a/git-rebase--interactive.sh
>> +++ b/git-rebase--interactive.sh
>> @@ -539,8 +539,8 @@ do_pick () {
>>                 git commit --allow-empty --allow-empty-message --amend \
>>                            --no-post-rewrite -n -q -C $1 &&
>>                         pick_one -n $1 &&
>> -                       git commit --allow-empty --allow-empty-message \
>> -                                  --amend --no-post-rewrite -n -q -C $1 \
>> +                       git commit --allow-empty --amend \
>> +                                  --no-post-rewrite -n -q \
>>                                    ${gpg_sign_opt:+"$gpg_sign_opt"} ||
>>                         die_with_patch $1 "Could not apply $1... $2"
>>         else
>> diff --git a/t/t3412-rebase-root.sh b/t/t3412-rebase-root.sh
>> index 0b52105..3608db4 100755
>> --- a/t/t3412-rebase-root.sh
>> +++ b/t/t3412-rebase-root.sh
>> @@ -278,4 +278,43 @@ test_expect_success 'rebase -i -p --root with conflict (second part)' '
>>         test_cmp expect-conflict-p out
>>  '
>>
>> +test_expect_success 'stop rebase --root on empty root log message' '
>> +       # create a root commit with a non-empty tree so that rebase does
>> +       # not fail because of an empty commit, and an empty log message
>> +       echo root-commit >file &&
>> +       git add file &&
>> +       tree=$(git write-tree) &&
>> +       root=$(git commit-tree $tree </dev/null) &&
>> +       git checkout -b no-message-root-commit $root &&
>> +       # do not ff because otherwise neither the patch nor the message
>> +       # are looked at and checked for emptiness
>> +       test_must_fail env EDITOR=true git rebase -i --force-rebase --root &&
>> +       echo root-commit >file.expected &&
>> +       test_cmp file file.expected &&
> 
> It is customary, and provides nicer diagnostic output upon failure, to
> have the "expected" file mentioned first:
> 
>     test_cmp file.expected file &&

Ok.

>> +       git rebase --abort
> 
> Do you want to place this under control of test_when_finished
> somewhere above the "git rebase" invocation to ensure cleanup if
> something fails before this point?

Thanks a lot for the hint, I will place the test_when_finished directly
above the rebase -i command line because it is not relevant before, the
exact position shouldn't matter though. I didn't know that test_run_
skips the cleanup code if -i (for immediate mode) is passed to the test
driver and the test case fails.

   Fabian

>> +'
>> +
>> +test_expect_success 'stop rebase --root on empty child log message' '
>> +       # create a root commit with a non-empty tree and provide a log
>> +       # message so that rebase does not fail until the root commit is
>> +       # successfully replayed
>> +       echo root-commit >file &&
>> +       git add file &&
>> +       tree=$(git write-tree) &&
>> +       root=$(git commit-tree $tree -m root-commit) &&
>> +       git checkout -b no-message-child-commit $root &&
>> +       # create a child commit with a non-empty patch so that rebase
>> +       # does not fail because of an empty commit, but an empty log
>> +       # message
>> +       echo child-commit >file &&
>> +       git add file &&
>> +       git commit --allow-empty-message --no-edit &&
>> +       # do not ff because otherwise neither the patch nor the message
>> +       # are looked at and checked for emptiness
>> +       test_must_fail env EDITOR=true git rebase -i --force-rebase --root &&
>> +       echo child-commit >file.expected &&
>> +       test_cmp file file.expected &&
>> +       git rebase --abort
> 
> Same two comments as for previous test.

Ok.

>> +'
>> +
>>  test_done