Unit tests should be mocking a created directory but are instead actually creating one when unit tests are run locally. Let's mock it instead of having a test create a directory for real.

On the command line, any of the steps can return <nil>, we instead want it to say what actually happened and not just the exit status 1. If it's indeed <nil>, let's return an empty string or generic message instead.

jhammond@alchemist $ alchemist --update    
Alchemist is updating brew...
This could take some time and may prompt for your password.
Alchemist has updated brew!
Alchemist has upgraded brew packages!
Alchemist has upgraded brew casks!
Alchemist has cleaned up brew!
Error while checking with brew doctor: exit status 1.
Alchemist has checked with brew doctor:
<nil>
Alchemist is finished updating brew!

Running brew doctor shows the real output:

jhammond@alchemist $ brew doctor
Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Some installed kegs have no formulae!
This means they were either deleted or installed with `brew diy`.
You should find replacements for the following formulae:
  brew-update
  brew-backup

I want Alchemist to be a single tool that can manage updating the platform's main package managers (Homebrew, Choco) under one roof.

Add the Choco package manager to this tool and build it on Windows. Have errors raised when you try to update brew on windows and when you try to update Choco on unix.

It would be awesome if we could upload the brew backup scripts as a GitHub gist (optional flag), this is importance so we can get an "off device" backup. It would also allow users to version control their backups.