def METHOD_NAME(self):
    v = vault.Vault(None, None)
    with mock.patch('boto.glacier.vault.ConcurrentUploader') as c:
        c.return_value.upload.return_value = 'archive_id'
        archive_id = v.concurrent_create_archive_from_file(
            'filename', 'my description')
        c.return_value.upload.assert_called_with('filename',
                                                 'my description')
    self.assertEqual(archive_id, 'archive_id')