tests: skip test_squashfs.py.test_superblock if squashfs is too old

# along with diffoscope.  If not, see <http://www.gnu.org/licenses/>.

import pytest

import subprocess

from diffoscope.comparators.squashfs import SquashfsFile

from utils import skip_unless_tools_exist, data, load_fixture, \

    assert_non_existing

    assert_non_existing, skip_unless_tool_is_older_than

def unsquashfs_version():

    # first line of 'unsquashfs -version' looks like:

    #   unsquashfs version 4.2-git (2013/03/13)

    try:

        out = subprocess.check_output(['unsquashfs', '-version'])

    except subprocess.CalledProcessError as e:

        out = e.output

    return out.decode('UTF-8').splitlines()[0].split()[2].strip()

squashfs1 = load_fixture(data('test1.squashfs'))

squashfs2 = load_fixture(data('test2.squashfs'))

def differences(squashfs1, squashfs2):

    return squashfs1.compare(squashfs2).details

@skip_unless_tools_exist('unsquashfs')

@skip_unless_tool_is_older_than('unsquashfs', unsquashfs_version, '4.3')

def test_superblock(differences):

    expected_diff = open(data('squashfs_superblock_expected_diff')).read()

    assert differences[0].unified_diff == expected_diff