import pytest
from src.instruments.real_dut import RealDUT
from src.instruments.simulated_dut import SimulatedDUT
from src.instruments.power_supply import PowerSupply
from src.interfaces.dummy import DummyBackend

def pytest_addoption(parser):
    parser.addoption("--sim", action="store_true", help="Use simulation mode")

@pytest.fixture
def sim_mode(request):
    return request.config.getoption("--sim")

@pytest.fixture
def dut(sim_mode):
    if sim_mode:
        return SimulatedDUT()
    return RealDUT()

@pytest.fixture
def power_supply(sim_mode):
    if sim_mode:
        return PowerSupply(DummyBackend())
    # TODO: Replace with real SCPI interface when ready
    raise NotImplementedError("Real power supply interface not yet implemented")