mockro

Mock MicroPython libraries for CPython development and testing.

mockro lets students write code that looks exactly like real MicroPython — import machine, import network, and so on — while running and testing it on a normal computer without any hardware attached.

Quick start

Install with uv:

uv add --dev mockro

Or with pip:

pip install mockro

Run a script with mocks

Once mockro is installed in the environment, plain Python invocations work:

uv run python main.py
# or
python main.py

You can also use the explicit wrappers:

mockro run main.py
# or
python -m mockro main.py

Run tests with mocks

mockro registers a pytest plugin. Just run:

pytest

and import machine will work in your tests and the code they import.

Note: by default mockro only installs MicroPython-specific module names such as machine, network, and usocket. It does not shadow CPython stdlib modules like socket, time, os, json, or asyncio, because those are needed by pytest and other tooling. Use usocket, utime, uos, ujson, and uasyncio in testable code, or run the code through mockro run / python -m mockro to get the non-u aliases as well.

Override behavior for assignments

In conftest.py or test fixtures:

import mockro

mockro.patch("machine.Pin.value", return_value=1)
mockro.patch("network.WLAN.isconnected", return_value=True)

Or temporarily:

with mockro.override(machine_Pin_value=1):
    ...

Create a new assignment

mockro init my_assignment

This scaffolds a project with pyproject.toml, conftest.py, starter source, tests, and .pyi stubs so editors know the mocked MicroPython APIs.

Mocked modules

mockro includes mocks for the full MicroPython standard library plus common port-specific modules:

• machine, network, bluetooth, framebuf, gc, micropython
• usocket / socket, utime / time, uos / os, usys / sys
• ujson / json, ubinascii / binascii, uhashlib / hashlib
• uerrno / errno, uheapq / heapq, uasyncio / asyncio
• uctypes / ctypes, ucollections / collections, ustruct / struct
• uselect / select, uzlib / zlib
• neopixel, dht, onewire, ds18x20
• esp, esp32, rp2, pyb, samd, zephyr

License

MIT