def test_pushing_locked_turnstile_remains_locked():
turnstile = Turnstile()
turnstile.push()
assert turnstile.current_state() == "locked"
def test_push_locks_previously_unlocked_turnstile():
turnstile = Turnstile(amount_for_passing=10)
turnstile.change_state(Unlocked(turnstile))
turnstile.push()
assert turnstile.current_state() == "locked"