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;
}