Re: [PATCH 1/2] t9902: verify that completion does not print anything

> Hi Patrick,
> 
> On Thu, 11 Jan 2024, Patrick Steinhardt wrote:
> 
> > The Bash completion script must not print anything to either stdout or
> > stderr. Instead, it is only expected to populate certain variables.
> > Tighten our `test_completion ()` test helper to verify this requirement.
> >
> > Signed-off-by: Patrick Steinhardt <ps@pks.im>
> > ---
> >  t/t9902-completion.sh | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
> > index aa9a614de3..78cb93bea7 100755
> > --- a/t/t9902-completion.sh
> > +++ b/t/t9902-completion.sh
> > @@ -87,9 +87,11 @@ test_completion ()
> >  	else
> >  		sed -e 's/Z$//' |sort >expected
> >  	fi &&
> > -	run_completion "$1" &&
> > +	run_completion "$1" >"$TRASH_DIRECTORY"/output 2>&1 &&
> >  	sort out >out_sorted &&
> > -	test_cmp expected out_sorted
> > +	test_cmp expected out_sorted &&
> > +	test_must_be_empty "$TRASH_DIRECTORY"/output &&
> 
> It seems that this fails CI on macOS, most likely because we're running
> with `set -x` and that output somehow ends up in `output`, see e.g. here:
> https://github.com/git/git/actions/runs/7496790359/job/20409405194#step:4:1880
> 
>   [...]
>   ++ test_completion 'git switch '
>   ++ test 1 -gt 1
>   ++ sed -e 's/Z$//'
>   ++ sort
>   ++ run_completion 'git switch '
>   ++ sort out
>   ++ test_cmp expected out_sorted
>   ++ test 2 -ne 2
>   ++ eval 'diff -u' '"$@"'
>   +++ diff -u expected out_sorted
>   ++ test_must_be_empty '/Users/runner/work/git/git/t/trash directory.t9902-completion/output'
>   ++ test 1 -ne 1
>   ++ test_path_is_file '/Users/runner/work/git/git/t/trash directory.t9902-completion/output'
>   ++ test 1 -ne 1
>   ++ test -f '/Users/runner/work/git/git/t/trash directory.t9902-completion/output'
>   ++ test -s '/Users/runner/work/git/git/t/trash directory.t9902-completion/output'
>   ++ echo ''\''/Users/runner/work/git/git/t/trash directory.t9902-completion/output'\'' is not empty, it contains:'
>   '/Users/runner/work/git/git/t/trash directory.t9902-completion/output' is not empty, it contains:
>   ++ cat '/Users/runner/work/git/git/t/trash directory.t9902-completion/output'
>   ++ local -a COMPREPLY _words
>   ++ local _cword
>   [...]
> 
> Maybe this is running in Dash and therefore `BASH_XTRACEFD=4` in
> `test-lib.sh` has not the intended effect?