DI is a pattern and there are frameworks that help you issuing them - no misunderstanding here. I just wanted to point out that using DI and a framework suppor

DI is a pattern and there are frameworks that help you issuing them - no misunderstanding here. I just wanted to point out that using DI and a framework supporting you using it, you are not in control what you get as dependency. Building the object graph yourself during test setup (and still respecting the rules of DI) will allow you that yet you have a lot more labor to do. In a modern language like C# with it's eco system it's hard and somethimes even impossible to avoid the DI feamework that connects all the services, therefore I was showing a way to get the same effect as the nullable pattern yet using a DI Framework during test setup.