A fake filesystem. Use it in your tests.
Mocha is great. But when your library is all about manipulating the filesystem, you really want to test the behavior and not the implementation. If you're mocking and stubbing every call to FileUtils or File, you're tightly coupling your tests with the implementation. With FakeFS:
Documentationsee README file.
released on 22 July 2009
This entry (in part or in whole) was last reviewed on 28 June 2010.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the page “GNU Free Documentation License”.
The copyright and license notices on this page only apply to the text on this page. Any software or copyright-licenses or other similar notices described in this text has its own copyright notice and license, which can usually be found in the distribution or license text itself.