tschaub/mock-fs — pull request #11 by tschaub (2014-05-16 18:55:55+00:00)
Title: Only call callback with two args if return is undefined

This makes `mock-fs` work with modules that check the function arity (e.g. `async`).

Thanks @bruse for finding the issue and providing the [test case](https://gist.github.com/bruse/5e5ba24bc5109090f75b). Fixes #10.