Python Mock And Libraries That Are Not Installed

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 (runs the motors): from RPi import GPIO as gpio

Solution 1:

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

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'>

In Python3 you have same behavior.

---

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'>