Added clarifications and changed the structure of the authorPosts state to be simpler.

The authors state consists of all the authors, posts and comments.

The order of the elements are based on the ordering of the allIds arrays. The ordering for them is in order of appearance.
If you mean ordering in the byId objects, this doesn't obviously matter since they are look-up tables.

The authorPosts state is now just simply and array of postIds for a user.

I updated the description to address all of these points.

Fixed!

Thank you for the feedback! Issue is fixed now.

Thank you for pointing this out! I have included a test to cover this.

Thank you for finding this oversight. The tests are now fixed with some of the cases having shuffled arrays.

Edited description to address the issue

Added 100 randomized tests