Testing things that work with filesystems

This section is all about how we can test things that interact with filesystems!

General principals

• Rather than test against an actual filesystem, we want to test against something that mimics a filesystem.
• We should use dependency injection to write code that works both against a real filesystem or against something that looks like a filesystem.

Libraries used

• https://github.com/spf13/afero - To act as a shim for our filesystem.
• https://github.com/stretchr/testify - A wrapper that makes testing a little easier.

Notes

The way I did dependency injection isn't super idiomatic. Ideally I'd have a struct that has a field of type afero.Fs, then a method on the struct that does the appending, plus a wrapper method that defaults the field with an afero.OsFs for ease of use.