Interface referencing an inner class of its implementation

Question

I am refactoring a piece of code and I have to made a method (lets call it myMethod ) in one class (let's call it TestImpl ) from private to public . Therefore, I try to add this method to its interface ( ITest ).

However, the problem is that a parameter of the method references to an inner class of TestImpl . ie something like:

myMethod (TestImpl.NewType var1, ...)

This seems a bit weird to me as the interface references to its own implementation. What is the best solution here? Or, is it really a problem?

Answer 1

As I understand it's static class, then it shouldn't be a problem. However, I think it's better to move that NewType out of TestImpl or even create new interface to generalize this NewType

Answer 2

It violates the DI principles, Interface should not have nay compile dependencies to its implementations. NewType should be extracted as a interface or class to outside.