Write to disk in Platform based JUnit tests

Hi,

I need to write JUnit tests for a NetBeans Platform project which needs to write a file to disk. The file is in runtime written to the user directory but during test execution to a virtual "nbfs" file system.
The file needs to be on disk in both cases as it will be used by another component which can handle real hard disk files only. Is there any way to force NbTest to create FileObject instances with createData(...) on hard disk? I read the FAQ articles about platform testing and FileUtil but could not find a solution yet.

Thanks,
Martin