python模拟和未安装的库

问题描述

我正在研究用于机器人的软件，该软件通常在Raspberry Pi上运行.让我们考虑两个文件的导入:

I am working on software for a robot, which is normally run on the Raspberry Pi. Let's consider the imports of two files:

motor.py(运行电动机):

from RPi import GPIO as gpio

和client.py(与服务器通信并将命令中继到电动机):

and client.py (communicates with the server and relays commands to the motors):

from rpi.motor import Motor

两个文件都位于名为rpi的目录中，该目录包含__init__.py和__main__.py. RPi软件包不能安装在非Rpi设备上.但是，我仍然想测试client.py的功能.

Both files are in a directory called rpi, which contains a __init__.py and a __main__.py. The RPi package cannot be installed on non-RPi devices. However, I still want to test the functionality of client.py.

import unittest
from unittest import mock
# Location A


class TestClient(unittest.TestCase):
    # Location B
    setUp(self):
         # Location C
         pass

最初，我在LocA上尝试了from rpi.client import Client，但是失败了，因为它尝试导入Motor，然后从RPi(不存在)导入GPIO.我也在LocB上尝试了mock.patch("rpi.client.Motor")(包括在self之后添加mock_motor，并在LocC上导入了Client，但是也失败了.我也尝试在LocA上模拟RPi，但是它没有用)要么.

Originally, I tried from rpi.client import Client at LocA, but that failed because it tried to import Motor, and then import GPIO from RPi, which doesn't exist. I also tried mock.patch("rpi.client.Motor") at LocB (including adding mock_motor after self, and imported Client at LocC, but that failed as well. I tried mocking RPi at LocA, too, but it didn't work either.

您如何模拟系统中未安装的库?

How do you mock out a library that is not installed on your system?

推荐答案

您可以使用 patch.dict() 修补sys.modules并模拟RPi模块，如指向的文档所示.

You can use patch.dict() to patch sys.modules and mock RPi module as showed in pointed documentation.

使用测试模块顶部的遵循代码:

Use follow code at the top of your test module:

>>> from mock import MagicMock, patch
>>> mymodule = MagicMock()
>>> patch.dict("sys.modules", RPi=mymodule).start()
>>> from RPi import GPIO as gpio
>>> gpio
<MagicMock name='mock.GPIO' id='139664555819920'>
>>> import os
>>> os
<module 'os' from '/usr/lib/python2.7/os.pyc'>

在Python3中，您具有相同的行为.

In Python3 you have same behavior.

在您的特定情况下，使用patch.dict有点过大；也许您对补丁程序上下文和原始状态恢复不感兴趣.因此，您可以通过直接设置sys.modules["RPi"]来简化它:

In your specific case use patch.dict is little bit overkill; maybe you aren't interested in patch context and original state recover. So you can simplify it by set sys.modules["RPi"] directly:

>>> from unittest.mock import MagicMock
>>> mymodule = MagicMock()
>>> import sys
>>> sys.modules["RPi"] = mymodule
>>> from RPi import GPIO as gpio
>>> gpio
<MagicMock name='mock.GPIO' id='140511459454648'>
>>> import os
>>> os
<module 'os' from '/usr/lib/python3.4/os.py'>

这篇关于python模拟和未安装的库的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！