Depends on the operating system, doesn't it?  On Win32 we probably will be setting all of these to 0 (except mode) because there isn't a sane concept of device or inode there, nor is there a great way to say the "group" or "user" of a file, since they use ACLs as their only access control system.

However, you could expose a package-only visible native method that tells you the *type* of the JNI support that is loaded (e.g. isPOSIX() method) and have the unit test probe that before making these assertions.  That way on Win32 we can assert that these are in fact 0.