'Assert that a particular block does not exist in a particular draft/published location.
Arguments:
block_type (str): The block-type of the XBlock to check.
block_id (str): The block-id of the XBlock to check.
draft (bool): If ``True``, assert that the block identified by ``block_type``
``block_id`` isn\'t a draft in the exported OLX.'

def assertOLXMissing(self, block_type, block_id, **kwargs):

    course_export_dir = self._get_course_export_dir()
    is_draft = kwargs.pop('draft', False)
    block_path = self._get_block_type_path(course_export_dir, block_type, is_draft)
    block_file_path = os.path.join(block_path, self._get_block_filename(block_id))
    self.assertFalse(os.path.exists(block_file_path), msg='{}    exists    but    should    not!'.format(block_file_path))
