I think I was confused because I naturally do what you say few people do. My external calls all parse into an object that you can then pass into the unit. It's

I think I was confused because I naturally do what you say few people do. My external calls all parse into an object that you can then pass into the unit. It's the integration tests job to ensure that the parse works. Then its the unit tests job to ensure that you run enough that you can be reasonably sure that you cover all cases.