gns3-server/tests/utils.py

# -*- coding: utf-8 -*-
#
# Copyright (C) 2015 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import asyncio
from unittest.mock import patch


class _asyncio_patch:
    """
    A wrapper around python patch supporting asyncio.
    Like the original patch you can use it as context
    manager (with) or decorator

    The original patch source code is the main source of
    inspiration:
    https://hg.python.org/cpython/file/3.4/Lib/unittest/mock.py
    """
    def __init__(self, function, *args, **kwargs):
        self.function = function
        self.args = args
        self.kwargs = kwargs

    def __enter__(self):
        """Used when enter in the with block"""
        self._patcher = patch(self.function, return_value=self._fake_anwser())
        self._patcher.start()

    def __exit__(self, *exc_info):
        """Used when leaving the with block"""
        self._patcher.stop()

    def __call__(self, func, *args, **kwargs):
        """Call is used when asyncio_patch is used as decorator"""
        @patch(self.function, return_value=self._fake_anwser())
        @asyncio.coroutine
        def inner(*a, **kw):
            return func(*a, **kw)
        return inner

    def _fake_anwser(self):
        future = asyncio.Future()
        future.set_result(self.kwargs["return_value"])
        return future


def asyncio_patch(function, *args, **kwargs):
    return _asyncio_patch(function, *args, **kwargs)