def get_dir_from_zipfile(zip_file, fallback=None):
    """Return the name of the root folder in a zip file.

    :param zip_file: a :class:`zipfile.ZipFile` instance.
    :param fallback: if `None`, the name of the zip file is used. This is
        returned if the zip file contains more than one top-level directory,
        or none at all.
    """
    fallback = fallback or zip_file.filename
    directories = [name for name in zip_file.namelist() if name.endswith("/")
                   and len(PurePath(name).parts) == 1]
    return fallback if len(directories) > 1 else directories[0]
def test_default_group(self):
        # It exists
        self.assertTrue(Group.objects.filter(name='Default').count() == 1)

        # Verify that all new users are assigned to default group
        u = User.objects.create_user(username="default_user")
        u.refresh_from_db()
        self.assertTrue(u.groups.filter(name='Default').count() == 1)