Re: [PATCH 1/3] t/checkout-last: checkout - doesn't work after rebase -i

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

Ramkumar Ramachandra <artagnon@gmail.com> writes:

> The following command
>
>   $ git checkout -
>
> does not work as expected after a 'git rebase -i'.
>
> Add a failing test documenting this bug.
>
> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
> ---
>  t/t2012-checkout-last.sh | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/t/t2012-checkout-last.sh b/t/t2012-checkout-last.sh
> index b44de9d..5729487 100755
> --- a/t/t2012-checkout-last.sh
> +++ b/t/t2012-checkout-last.sh
> @@ -116,4 +116,12 @@ test_expect_success 'master...' '
>  	test "z$(git rev-parse --verify HEAD)" = "z$(git rev-parse --verify master^)"
>  '
>  
> +test_expect_failure '"checkout -" works after an interactive rebase' '
> +	git checkout master &&
> +	git checkout other &&
> +	git rebase -i master &&
> +	git checkout - &&
> +	test "z$(git symbolic-ref HEAD)" = "zrefs/heads/master"
> +'

Hmph, you were on "other" and then ran "rebase -i" to rebase it.
When you are done, you are on "other".  You want to go back to the
one before you checked out the branch you started your "rebase -i"
on, which is "master".

OK, the expectation makes sense to me.

These four are all valid ways to spell the "rebase -i master" step.

	git rebase -i master
        git rebase -i --onto master master
        git rebase -i master other
        git rebase -i --onto master master other

and I think it is sensible to expect

 (1) they all behave the same way; or

 (2) the first two behave the same, but the latter two explicitly
     checks out 'other' by giving the last argument.  If you are not
     on 'other' when you run the "rebase -i", "checkout -" should
     come back to the branch before 'other', i.e. the branch you
     started your "rebase -i" on.

In other words, (2) would mean:

	git checkout master &&
        git checkout -b naster &&
        git rebase -i master other &&
	# ends up on other
        test_string_equal "$(git symbolic-ref HEAD)" refs/heads/other &&
        git checkout - &&
	# we were on naster before we rebased 'other'
        test_string_equal "$(git symbolic-ref HEAD)" refs/heads/naster

It is a bit unclear what the following should expect.

	git checkout master &&
        git checkout other &&
        git rebase -i master other &&
	# ends up on other
        test_string_equal "$(git symbolic-ref HEAD)" refs/heads/other &&
        git checkout - &&
	# we are on ??? before we rebased other
        test_string_equal "$(git symbolic-ref HEAD)" refs/heads/???

One could argue that the "first checkout other and then rebase" done
by rebase becomes a no-op and the user should be aware of that
because rebase is started while on that other branch, in which case
we should come back to 'master'.  From consistency point of view,
one could instead argue that we were on 'other' before we rebased
it, in which case it may not be unreasonable for "checkout -" to
come back to 'other'.  I tend to prefer the former (i.e. go back to
'master') over the latter but not by a large margin.