It depends on how you define your 'unit'; a unit can be as large or as small as you require. But, I'd suggest if you can't test a single class in isolation eas

It depends on how you define your 'unit'; a unit can be as large or as small as you require. But, I'd suggest if you can't test a single class in isolation easily (and you might need fakes/mocks) then the class probably needs redesigning.