Re: [PATCH v2] t/test-lib: make `test_dir_is_empty` more robust

> While the `test_dir_is_empty` function appears correct in most normal
> use cases, it can fail when filenames contain newlines. This patch
> changes the implementation to use `ls -A`, which is specified by POSIX.
> The output should be empty exactly if the directory is empty.
> 
> The newly added unit test fails before this change and passes after it.
> 
> Signed-off-by: William Chargin <wchargin@gmail.com>
> ---
> 
> I originally wrote this patch for the standalone Sharness library, but
> that library advises that such patches be sent to the Git mailing list
> first.
> 
>   t/t0000-basic.sh        | 29 +++++++++++++++++++++++++++++
>   t/test-lib-functions.sh |  2 +-
>   2 files changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
> index 34859fe4a..3885b26f9 100755
> --- a/t/t0000-basic.sh
> +++ b/t/t0000-basic.sh
> @@ -821,6 +821,35 @@ test_expect_success 'tests clean up even on failures' "
>   	EOF
>   "
>   
> +test_expect_success 'test_dir_is_empty behaves even in pathological cases' "
> +	run_sub_test_lib_test \
> +		dir-empty 'behavior of test_dir_is_empty' <<-\\EOF &&
> +	test_expect_success 'should pass with actually empty directory' '
> +		mkdir empty_dir &&
> +		test_dir_is_empty empty_dir
> +	'
> +	test_expect_success 'should fail with a normal filename' '
> +		mkdir nonempty_dir &&
> +		touch nonempty_dir/some_file &&
> +		test_must_fail test_dir_is_empty nonempty_dir
> +	'
> +	test_expect_success 'should fail with dot-newline-dot filename' '
> +		mkdir pathological_dir &&
> +		printf \"pathological_dir/.\\\\n.\\\\0\" | xargs -0 touch &&
> +		test_must_fail test_dir_is_empty pathological_dir
> +	'
> +	test_done
> +	EOF
> +	check_sub_test_lib_test dir-empty <<-\\EOF
> +	> ok 1 - should pass with actually empty directory
> +	> ok 2 - should fail with a normal filename
> +	> ok 3 - should fail with dot-newline-dot filename
> +	> # passed all 3 test(s)
> +	> 1..3
> +	EOF
> +"
> +
> +
>   ################################################################
>   # Basics of the basics
>   
> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
> index 2b2181dca..f7ff28ef6 100644
> --- a/t/test-lib-functions.sh
> +++ b/t/test-lib-functions.sh
> @@ -568,7 +568,7 @@ test_path_is_dir () {
>   # Check if the directory exists and is empty as expected, barf otherwise.
>   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
>   	then
>   		echo "Directory '$1' is not empty, it contains:"
>   		ls -la "$1"
>