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 setUp(self):
        super(ExplorationVoiceoverApplicationUnitTest, self).setUp()
        self.signup('author@example.com', 'author')
        self.author_id = self.get_user_id_from_email('author@example.com')

        self.signup('reviewer@example.com', 'reviewer')
        self.reviewer_id = self.get_user_id_from_email('reviewer@example.com')

        self.voiceover_application = (
            suggestion_registry.ExplorationVoiceoverApplication(
                'application_id', 'exp_id', suggestion_models.STATUS_IN_REVIEW,
                self.author_id, None, 'en', 'audio_file.mp3', '<p>Content</p>',
                None))