Any other ideas on how to write testable code which uses this filesystem API? not nice ones (or I must be missing something). Could either make all code take t

Any other ideas on how to write testable code which uses this filesystem API? not nice ones (or I must be missing something). Could either make all code take the API as a template parameter, or wrap the API in your own set of classes. Now often the logic you really want to (unit) test isn't the one directly accessing the filesystem but rather a layer higher? And in case of integration/system tests (or whatever it's called these days) wouldn't you rather use the actual filesystem, like with the temp directory you talk about? Can you provide a concrete example of what would be hard to test with this?