I find structural typing is mostly necessary when someone messed up and used a class where an interface should have been used. I'm now currently in the positio

I find structural typing is mostly necessary when someone messed up and used a class where an interface should have been used. I'm now currently in the position of having to decide whether it's better to accept defeat or use T4 or similar to write the 1000+ line wrapper class to undo the mistake... You'd think Microsoft would at least remember to do dependency inversion through interfaces in their own C# code.