Re: [PATCH 1/1] t/test-lib: make `test_dir_is_empty` more robust

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Aug 5, 2018, 05:23 UTC
Message-ID: <CAPig+cQSryjWrFZML_g0fR5oq6dzVaWPXm_4R-Jg_ay1R2DzbQ@mail.gmail.com>
In-Reply-To: <20180805041956.GI258270@aiede.svl.corp.google.com>

On Sun, Aug 5, 2018 at 12:20 AM Jonathan Nieder <jrnieder@gmail.com> wrote:

Show 16 quoted lines

> William Chargin wrote:
> >  test_dir_is_empty () {
> >       test_path_is_dir "$1" &&
> > -     if test -n "$(ls -a1 "$1" | egrep -v '^\.\.?$')"
> > +     if test "$(ls -A1 "$1" | wc -c)" != 0
>
> Another portability gotcha: wc output includes a space on Mac so this
> test would always return true there.  How about
>
>         if test -n "$(ls -A1 "$1")"
>
> "ls -A" was added in POSIX.1-2017. [...]
> That's very recent, but the widespread implementation it mentions is
> less so.  This would be our first use of "ls -A", so I'd be interested
> to hear from people on more obscure platforms.  It does seem to be
> widespread.

A simpler approach, without the portability concerns of -A, would be to remove the "." and ".." lines from the top of the listing:

    ls -f1 "$1" | sed '1,2d'

If we're worried about -f not being sufficiently portable, then an even simpler approach would be to check whether the output of 'ls -a1' has more lines than the two expected ("." and ".."):

    test $(ls -a1 "$1" | wc -l) -gt 2

I think I favor this final implementation over the others.