I encountered the following error when running the unit tests...
This appears to be caused by the fact that get_max_upload_file_size() is returning nothing when my upload limit is set to 2GB (2048MB for post_max_size and upload_max_filesize in php.ini).
It looks like this is caused because my PHP instance is 32bit (running on a 64bit machine) and 2147483648 exceeds limits.
The list of possible upload limits provided by get_max_upload_sizes() is...
Oddly, the limiting of file sizes seems to work still, although I haven't tested this very extensively. I assume this is because the site limit of zero is being used.