Re: [PATCH 04/11] t3030-merge-recursive: don't check the stderr of a subshell

["SZEDER Gábor" <szeder.dev@gmail.com>]

On Tue, Feb 27, 2018 at 10:10 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Junio C Hamano <gitster@pobox.com> writes:
>
>> SZEDER Gábor <szeder.dev@gmail.com> writes:
>>
>>> The two test checking 'git mmerge-recursive' in an empty worktree in
>>> ...
>>>              GIT_INDEX_FILE="$PWD/ours-has-rename-index" &&
>>>              export GIT_INDEX_FILE &&
>>>              mkdir "$GIT_WORK_TREE" &&
>>> -            git read-tree -i -m $c7 &&
>>> -            git update-index --ignore-missing --refresh &&
>>> -            git merge-recursive $c0 -- $c7 $c3 &&
>>> -            git ls-files -s >actual-files
>>> -    ) 2>actual-err &&
>>> -    >expected-err &&
>>> +            git read-tree -i -m $c7 2>actual-err &&
>>> +            test_must_be_empty expected-err &&
>>> +            git update-index --ignore-missing --refresh 2>actual-err &&
>>> +            test_must_be_empty expected-err &&
>>> +            git merge-recursive $c0 -- $c7 $c3 2>actual-err &&
>>> +            test_must_be_empty expected-err &&
>>> +            git ls-files -s >actual-files 2>actual-err &&
>>> +            test_must_be_empty expected-err
>>
>> Where do the contents of all of these expected-err files come from?
>> Should all of the test_must_be_empty checks be checking actual-err
>> instead?

Ugh, I messed that up.

> And the reason why your pre-submission testing did not catch may be
> because test_must_be_empty is broken?  I wonder if this is a good
> way forward to catch a possible bug like this.

Yeah.  'test -s file' means "exists and has a size greater than zero",
so the missing file doesn't trigger the error code path.

> Of course, if somebody was using the helepr for "must be either
> missing or empty", this change will break it, but I somehow doubt
> it.

FWIW, I just run the test suite with this change added, and there were
no failures.  I think it's a good change.

>  A program that creates/opens and writes an error message only
> when an error is detected is certainly possible, and could be tested
> with the current test_must_be_empty this way:
>
>         rm -f actual-err &&
>         git frotz --error-to=actual-err &&
>         test_must_be_empty actual-err
>
> but then the last step in such a test like the above is more natural
> to check if actual-err _exists_ in the first place anyway, so...
>
>  t/test-lib-functions.sh | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
> index 37eb34044a..6cfbee60e4 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -772,7 +772,11 @@ verbose () {
>  # otherwise.
>
>  test_must_be_empty () {
> -       if test -s "$1"
> +       if ! test -f "$1"
> +       then
> +               echo "'$1' is missing"
> +               return 1
> +       elif test -s "$1"
>         then
>                 echo "'$1' is not empty, it contains:"
>                 cat "$1"