Afero
A FileSystem abstraction system for Go
...Afero is also a library providing a base set of interoperable backend filesystems that make it easy to work with afero while retaining all the power and benefit of the os and ioutil packages. Afero provides significant improvements over using the os package alone, most notably the ability to create mock and testing filesystems without relying on the disk. It is suitable for use in any situation where you would consider using the OS package as it provides an additional abstraction that makes it easy to use a memory backed file system during testing. It also adds support for the http filesystem for full interoperability.