Bitbangio Tests

These tests run under CPython, and are intended to verify that the library passes some sanity checks, using a lightweight simulator as the target device.

These tests run automatically from the standard circuitpython github workflow. To run them manually, first install these packages if necessary:

$ pip3 install pytest

Then ensure you're in the root directory of the repository and run the following command:

$ python -m pytest

Notes on the simulator

simulator.py implements a small logic level simulator and a few test doubles so the library can run under CPython.

The Engine class is used as a singleton in the module to co-ordinate the simulation.

A Net holds a list of FakePins that are connected together. It also resolves the overall logic level of the net when a FakePin is updated. It can optionally hold a history of logic level changes, which may be useful for testing some timing expectations, or export them as a VCD file for Pulseview. Test code can also register listeners on a Net when the net's level changes, so it can simulate device behavior.

A FakePin is a test double for the CircuitPython Pin class, and implements all the functionality so it behaves appropriately in CPython.

A simulated device can create a FakePin for each of its terminals, and connect them to one or more Net instances. It can listen for level changes on the Net, and bitbang the FakePin to simulate behavior. simulated_spi_device.py implements a peripheral device that writes a constant value onto an SPI bus.