[taberiand]

As the other commenter points out, I believe you are conflating DI implementations with Dependency Injection as a methodology. But I suppose I am too, because really I'm talking about using dependency injection to achieve Dependency Inversion - the D of the SOLID design principles.

There are good and bad implementations of dependency injection (or, perhaps, appropriate and inappropriate depending on requirements), but the principle of dependency inversion applies at an architectural level, before specifics of implementation and things like unit testing come into play