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

[Jens Lehmann <Jens.Lehmann@web.de>]

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
> --
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