I haven't tried Directory::Scratch, but it looks pretty nice. It's specifically written to handle cross-platform issues with temporary test files. From Directory::Scratch:

When writing test suites for modules that operate on files, it's often inconvenient to correctly create a platform-independent temporary storage space, manipulate files inside it, then clean it up when the test exits. /.../ This module aims to eliminate that problem by making it easy to do things right.

It may be overkill if you only want to create only one file though.

lodin