Delphi-PRAXiS - Unittests in Bold. Is it possible ?

I started to explore interfaces. One of the reasons I want to know more about interfaces is that I want to use unittests. Interfaces are a key part that makes it easier to make the code more testable.
I worked with Delphi for a long time and I know the concept behind interfaces but never really created new ones and used them. I believe one reason for this is that Bold generates code for classes in the model in one file businessclasses.pas. businessclasses.pas is a hotspot. It must be included