rspec/rspec-rails — pull request #940 by srowley (2014-02-23 05:11:26+00:00)
Title: be_a_new matcher matches based on new_record?, not persisted?

This behavior is inconsistent with the comments, but not with the README. Personally I prefer `persisted?` because it is implemented by both ActiveModel and ActiveRecord, as opposed to `new_record?`, which is only available in ActiveRecord to my knowledge.

If this is by design, it would be good to update the comments to reflect that.