LinUSBConverter

"""Shared pytest fixtures for the ucanlintools test suite.

Hardware tests need uCAN LIN USB converters. By default the master dongle is
expected on COM3 and the slave dongle on COM33; override with the environment
variables ``LUC_MASTER_PORT`` and ``LUC_SLAVE_PORT``. Any hardware test whose
required port cannot be opened is skipped rather than failed, so the offline
tests always run.
"""
import os
import time

import pytest
import serial

HERE = os.path.dirname(__file__)
SAMPLE_LDF = os.path.join(HERE, "fixtures", "sample.ldf")

MASTER_PORT = os.environ.get("LUC_MASTER_PORT", "COM3")
SLAVE_PORT = os.environ.get("LUC_SLAVE_PORT", "COM33")


def _port_available(port):
    """Return True if the serial port can actually be opened."""
    try:
        s = serial.Serial(port, timeout=0.1, baudrate=19200)
    except Exception:
        return False
    s.close()
    # Windows can briefly hold the handle after close; give it a moment so the
    # test that follows can reopen the port.
    time.sleep(0.05)
    return True


@pytest.fixture(scope="session")
def sample_ldf_path():
    return SAMPLE_LDF


@pytest.fixture
def master_port():
    if not _port_available(MASTER_PORT):
        pytest.skip(f"master LIN dongle {MASTER_PORT} not available")
    return MASTER_PORT


@pytest.fixture
def slave_port():
    if not _port_available(SLAVE_PORT):
        pytest.skip(f"slave LIN dongle {SLAVE_PORT} not available")
    return SLAVE_PORT