Answers

1. Interfaces benefit us when writing modular code that’s decoupled and reduces dependency across different parts of the code base. Since we have an interface, it’s much easier to swap out the implementation. In the existing code, you’d swap the implementation type in the Run method of the metadata package.
2. In this example:

    ./audiofile-cli upload -filename music.mp3

upload, -filename, and music.mp3 are all considered arguments. However, flags are specific arguments that are specifically marked by a specific syntax. In this case, -filename is a flag.

3. An additional test for when a user runs the get command without passing in any arguments or flags would look like this:

        {
           name: "get - failure - missing required id flag",
           fields: fields{
              ...