def METHOD_NAME(add_battery_assets, process, process_type, optimal_start):
    """
    Test scheduling a process of 4kW of power that last 4h using the ProcessScheduler
    without time restrictions.
    """
    # get the sensors from the database
    epex_da = Sensor.query.filter(Sensor.name == "epex_da").one_or_none()
    flex_model = {
        "duration": "PT4H",
        "process-type": process_type,
        "power": 4,
    }
    flex_context = {
        "consumption-price-sensor": epex_da.id,
    }
    scheduler = ProcessScheduler(
        process,
        start,
        end,
        resolution,
        flex_model=flex_model,
        flex_context=flex_context,
    )
    schedule = scheduler.compute()
    optimal_start = tz.localize(optimal_start)
    mask = (optimal_start <= schedule.index) & (
        schedule.index < optimal_start + timedelta(hours=4)
    )
    assert (schedule[mask] == 4).all()
    assert (schedule[~mask] == 0).all()