如何在c＃中测试视图模型是否处于设计器模式

I'm new to C# and WPF, so I wanted to start by the book with MVVM. I have a small WPF app and I'd like to test if my view model is created in Designer mode or not (checking DesignerProperties); given that I have an IDataService that provides data to the ViewModel either from a hardcoded list (Design time) or a REST service (Runtime).I'm new to C# and WPF, so I wanted to start by