奇怪现象，父类构造函数中的赋值子类无法取得

实战中这样的类，Shize保持了原始值， 但单元测试，又是好的，很奇怪。

public abstract class GrandPa 
{
    protected int Nothing;
    protected GrandPa(int nothing)=> Nothing = nothing;

}

public abstract class Father : GrandPa
{
    protected readonly long Shize;
    protected Father(int nothing): base(nothing)
    {
        Shize = DateTime.Now.ToTimeStampInSecond();
    }
}
public class Son : Father
{
    public Son(int nothing) : base(nothing)
    {
    }
    public long GetShiZe() => Shize;
}