Marks 3rd party test library as private dependency

[aaronbrethorst]

This change means that consumers of the BulletinBoard library using Carthage will no longer have to take the snapshot test case library as a direct dependency of their own project when using BulletinBoard. The snapshot test case library will still be available to library developers as normal. carthage update, carthage bootstrap, etc. will all still work without change.

More information here: https://github.com/Carthage/Carthage/blob/master/Documentation/Artifacts.md

Checklist

• I've tested my changes.
• I've read the Contribution Guidelines.
• I've updated the documentation if necessary.

Motivation and Context

My project uses Bulletin Board, and it is meant to be consumed by other projects as a framework. I don't want to make my users dependent on the snapshot test case library used in this project. By moving the dependency into the Cartfile.private file, this problem is solved.

[alexisakers]

This is super thoughtful, thanks! Do I need to do anything for the change to be taken into account (making a new release?)

[aaronbrethorst]

For my project, I'm currently using my fork aaronbrethorst/BulletinBoard with the private-deps branch. I'm happy to keep using it for the time being, so don't worry about creating a new release for the time being. The next time you make a release, the change should cascade down to all Carthage users automatically.

[aaronbrethorst]

Sorry, to actually answer your question: for this change to be made available to Carthage users, you will need to publish a new release. Technically, I think this may constitute a breaking change if people are using the implicit dependency on the snapshot test case library to pull it in to their own projects, so it may be worth holding back from a release for the time being.