Why??

I do a lot of development on my Powerbook and I got tired of constantly creating a fake interface for dev on my laptop and testing on Travis.ci or github workflows.

• 2017 Apr 2: Beta Quality
• 2017 Apr 8: Initial python3 support

So, does this simulate everything on a Raspberry Pi? No! Right now it simulates what I use and need. Over time, more will be added. You are also welcome to submit pull requests for things I haven't added yet.

The preferred way to install this is:

pip install fake_rpi

To submit pull requests for new sensors or fixes, just do:

git clone https://github.com/MomsFriendlyRobotCompany/fake_rpi.git
cd fake_rpi
poetry install

Then do a pull request.

To fake RPi.GPIO or smbus, this following code must be executed before your application:

# Replace libraries by fake ones
import sys
import fake_rpi

sys.modules['RPi'] = fake_rpi.RPi     # Fake RPi
sys.modules['RPi.GPIO'] = fake_rpi.RPi.GPIO # Fake GPIO
sys.modules['smbus'] = fake_rpi.smbus # Fake smbus (I2C)

Then you can keep your usual imports in your application:

import RPi.GPIO as GPIO
import smbus

GPIO.setmode(io.BCM) # now use the fake GPIO
b = GPIO.input(21)

sm = smbus.SMBus(1) # now use the fake smbus
b = sm.read_byte_data(0x21, 0x32)  # read in a byte

Turning on/off fake calls logging:

from fake_rpi import toggle_print

# by default it prints everything to std.error
toggle_print(False)  # turn on/off printing

But I need smbus to return a specific byte for unit testing! Ok, then create a child of my smbus like below and modify only the methods you need changed:

from fake_rpi import smbus
from fake_rpi import printf

class MyBus(smbus.SMBus):
    @printf
    def read_byte_data(self, i2c_addr, register):
        ret = 0xff
        if i2c_addr == 0x21:
            ret = 0x55
        elif i2c_addr == 0x25:
            ret = 0x11
        return ret

sm = MyBus()
b = sm.read_byte_data(0x21, 0x32)  # read in a byte

Here is the output from example.py in the git repo when the printing is toggled on or off:

kevin@Logan fake_rpi $ ./example.py
<<< WARNING: using fake raspberry pi interfaces >>>

kevin@Logan fake_rpi $ ./example.py
<<< WARNING: using fake raspberry pi interfaces >>>
fake_rpi.RPi.PWM.__init__()
fake_rpi.RPi.PWM.start(5,)
fake_rpi.smbus.SMBus.__init__(1,)
fake_rpi.smbus.SMBus.write_byte_data(1, 2, 3)
fake_rpi.smbus.SMBus.read_byte_data(1, 2): 21
fake_rpi.smbus.SMBus.close()
__main__.MyBus.__init__()
__main__.MyBus.read_byte_data(1, 2): 72
__main__.MyBus.read_i2c_block_data(1, 2, 3): [90, 90, 90]

Copyright (c) 2017 Kevin J. Walchko

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.