from trainsim.config_loader import SimParams
from trainsim.physics import Train


def test_train_accelerates_with_traction():
    p = SimParams(1000, 20, 0.15, 0.25, 0.02, 25)
    t = Train()
    t.sim_running = True
    t.actuate(100, 0)
    for _ in range(120):
        t.tick(p, 0.05)
    assert t.speed_mps > 0.5


def test_brake_slows_train():
    p = SimParams(1000, 20, 0.15, 0.25, 0.02, 25)
    t = Train(speed_mps=10.0)
    t.sim_running = True
    t.actuate(0, 100)
    for _ in range(200):
        t.tick(p, 0.05)
    assert t.speed_mps < 10.0