Unable to unit test code containing *_uploaded_file()

Hello! I use PHPUnit for unit testing of my application (but this issue is independent of PHPUnit). Tests are run from command line so it's not way (that I can imagine) to simulate file upload, because app code uses is_uploaded_file() to check if file was really uploaded. In my opionion some functions for simulation of file upload in command line script would be very handy for unit testing. What I mean is adding a function or a set of functions for setting file upload, for example: do_file_upload( upload_params, upload data). This function would be for use only in testing code, so there would be no need to change existing application code to add unit tests, and what's more important it would not leak to security risk. Regards, Piotr Czachur