Mechanism Developers Guide

Mechanism Developers Guide#

Introduction#

Fuze™ Test supports pluggable control and acquisition “mechanisms”—Python classes that interact with hardware (e.g. flash programmers, relays, GPIO, CAN).

These mechanisms implement a shared interface and can be referenced in test case JSON as command types.

This guide describes how to build and integrate new mechanisms.

Core Interface#

All mechanism classes must inherit from:

class TestCommandRunnerIF(object):
    def __init__(self):
        pass

    def run(self, command_dict):
        raise NotImplementedError("Mechanism must implement `run()`")

Your mechanism must implement run(command_dict) to perform the actual work.

Available implementations include:

  • TcsCommandRunner — for structured command sequences

  • CfeCommandRunner — for CFE-based communication

  • CssCommandRunner — for device state control

Creating a New Mechanism#

  1. Subclass TestCommandRunnerIF:

class MyCustomRunner(TestCommandRunnerIF):
    def run(self, command_dict):
        port = command_dict["port"]
        signal = command_dict["signal"]
        self.toggle_gpio(port, signal)

  1. Define your logic in run().

  2. Optionally add init parameters (e.g. serial port, config).

  3. Place your file under:

producttest/pta_functions/

Referencing from Test JSON#

Each test case defines commands like this:

{
    "TYPE": "MYRUNNER",
    "CMD": {
        "port": 17,
        "signal": 1
    }
}

The TYPE string must match what the PTA factory uses to map to your runner class.

Factory Registration#

You may need to modify the command dispatcher in ProductTestAdapter to add a mapping:

if cmd["TYPE"] == "MYRUNNER":
    runner = MyCustomRunner()
    runner.run(cmd["CMD"])

Make sure to log errors, validate inputs, and return success/failure markers.

Testing and Debugging#

  • Use the FUZE_DEBUG=1 env var to enable verbose logs.

  • Write unit tests that call your runner directly.

  • Reuse ptalogging.logger for consistent logging format.

  • Confirm your mechanism integrates by executing a minimal test case.

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