public void GearDownTest()
{
CarModel target = new CarModel(); // TODO: 初始化为适当的值
target = null;
// int p =target.GetHashCode();
//哈希值并不因为内部变量而有变化
target.GearDown();
//Assert.AreEqual(p, target.GetHashCode());
//Assert.Inconclusive("无法验证不返回值的方法。");
}