def METHOD_NAME(self):
    generator = BareResourceGenerator()
    generator.data = MagicMock(
        return_value=[
            {"type": "html", "data": "", "thumbnail": True},
            {"type": "html", "data": "", "thumbnail": True}
        ]
    )
    self.assertRaises(
        MoreThanOneThumbnailPageFoundError,
        generator.generate_thumbnail,
    )