Thanks for the feedback, but I think we are keeping up, even if it might not be obvious from the TOC.
While the currently-released version does cover Action Cable, the 5.1 update that’s in beta now covers:
- system testing (new in Rails 5.1)
- Active Job (not new, but missing previously)
- Heroku deployments
- other small additions to Rails 5.1
- Supplemental material on RSpec, Slim, and CSS Next
We’ve tried to address the marquee features of Rails as much as we could, and I think we’ve done that. The latest beta has everything I’ve listed above (as well as Action Cable). Would love your feedback on it…I’m hard pressed to find a top-line Rails feature we aren’t addressing.