Re: [RFC/PATCH 1/4] test-lib: add test_dir_is_empty()

[Michael Haggerty <mhagger@alum.mit.edu>]

On 03/26/2014 09:29 AM, Jens Lehmann wrote:
> Am 25.03.2014 21:49, schrieb Junio C Hamano:
>> Jens Lehmann <Jens.Lehmann@web.de> writes:
>>
>>> For the upcoming submodule test framework we often need to assert that an
>>> empty directory exists in the work tree. Add the test_dir_is_empty()
>>> function which asserts that the given argument is an empty directory.
>>>
>>> Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
>>> ---
>>>
>>> I believe this one is pretty straightforward (unless I missed that this
>>> functionality already exists someplace I forgot to look ;-).
>>
>> I am not very thrilled to see that it depends on "." and ".." to
>> always exist, which may be true for all POSIX filesystems, but
>> still...
> 
> Agreed. I didn't find any one-liners to do that ("ls -A" isn't
> POSIX), so I decided to wrap that in a function. Testing that
> "rmdir" on the directory succeeds (because the directory is
> empty) would kinda work, but then we'd have to re-create the
> directory afterwards, which really doesn't sound like a good
> strategy either as the test would manipulate the to-be-tested
> object. I'm not terribly happy with depending on "." and ".."
> either, but couldn't come up with something better. At least
> the test should fail for any filesystem not having the dot
> files ...
> 
>> Do expected callsites of this helper care if "$1" is a symbolic link
>> that points at an empty directory?
> 
> Yep, a symbolic link pointing to an empty directory should make
> the test fail.
> 
>> What do expected callsites really want to ensure?  In other words,
>> why do they care if the directory is empty?  Is it to make sure,
>> after some operation, they can "rmdir" the directory?
> 
> To assert that a submodule is created but *not* populated. This
> is intended to catch any possible fallout from the recursive
> checkout later, in case that would kick in when it shouldn't.
> 
>>>  t/test-lib-functions.sh | 11 +++++++++++
>>>  1 file changed, 11 insertions(+)
>>>
>>> diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
>>> index 158e10a..93d10cd 100644
>>> --- a/t/test-lib-functions.sh
>>> +++ b/t/test-lib-functions.sh
>>> @@ -489,6 +489,17 @@ test_path_is_dir () {
>>>  	fi
>>>  }
>>>
>>> +# Check if the directory exists and is empty as expected, barf otherwise.
>>> +test_dir_is_empty () {
>>> +	test_path_is_dir "$1" &&
>>> +	if test $(ls -a1 "$1" | wc -l) != 2
>>> +	then
>>> +		echo "Directory '$1' is not empty, it contains:"
>>> +		ls -la "$1"
>>> +		return 1
>>> +	fi
>>> +}
>>> +
>>>  test_path_is_missing () {
>>>  	if [ -e "$1" ]
>>>  	then

Why not do something like

    test -z "$(ls -a1 "$1" | egrep -v '^\.\.?$')"

I.e., make the test ignore "." and ".." without depending on their
existence?

Michael

-- 
Michael Haggerty
mhagger@alum.mit.edu
http://softwareswirl.blogspot.com/