Parallel Test Execution Strategies

"""Configure pytest-xdist for ECU test parallelism."""

# conftest.py additions for parallel execution
import pytest

def pytest_configure(config):
    """Register worker ID as a fixture."""
    pass

@pytest.fixture(scope="session")
def worker_id(request):
    """Get pytest-xdist worker ID for isolated resources."""
    if hasattr(request.config, "workerinput"):
        return request.config.workerinput["workerid"]
    return "master"

@pytest.fixture(scope="session")
def ecu(request, worker_id):
    """Session ECU with per-worker CAN channel isolation."""
    channel_map = {
        "master": "vcan0",
        "gw0":    "vcan0",
        "gw1":    "vcan1",
        "gw2":    "vcan2",
        "gw3":    "vcan3",
    }
    channel = channel_map.get(worker_id, "vcan0")
    if channel == "mock":
        from lib.mock_ecu import MockAebEcu
        return MockAebEcu(worker_id=worker_id)
    from lib.can_ecu import CanAebEcu
    return CanAebEcu(channel, request.config.getoption("--dbc"))

"""Rules for parallel test isolation."""

# SAFE for parallelism:
# - Tests that use only mock ECU (no shared state)
# - Tests that use different vcan interfaces (vcan0, vcan1...)
# - Tests that are purely computational (signal calculations)

# UNSAFE for parallelism (must run sequentially):
# - Tests that read/write to shared ECU state (NVM, DTCs)
# - Tests that change ECU diagnostic session
# - Tests that require exclusive HiL rig access

import pytest

# Mark tests that cannot run in parallel
SERIAL_MARKS = [pytest.mark.serial]

def pytest_collection_modifyitems(items, config):
    """Move serial tests to the end; run them after parallel tests."""
    serial = [i for i in items if i.get_closest_marker("serial")]
    parallel = [i for i in items if not i.get_closest_marker("serial")]
    items[:] = parallel + serial