def METHOD_NAME(self):
    with open(os.path.join(self.config.config_dir,
                           ".pluginstorage.json"), "w") as fh:
        fh.write("dummy")
    # When unable to read file that exists
    mock_open = mock.mock_open()
    mock_open.side_effect = IOError
    self.plugin.storage._storagepath = os.path.join(self.config.config_dir,
                                                   ".pluginstorage.json")
    with mock.patch("builtins.open", mock_open):
        with mock.patch('certbot.compat.os.path.isfile', return_value=True):
            with mock.patch("certbot.reverter.util"):
                with pytest.raises(errors.PluginStorageError):
                    self.plugin.storage._load()  # pylint: disable=protected-access