An issue with cable.js after rails 4.2.2 - 5.0.0.1 update

I upgraded a copy of my rails 4.2.2 application to rails 5.0.0.1, following instructions at railsapp and at edgeguides.rubyonrails.org
Most of my work consisted in consulting railsdiff.org, thus copying and pasting new code to my application.

After completing all the necessary revisions and running tests, I was warned about some issues.
Line 6 of app/assets/javascripts/cable.js``` (copied from railsdiff.org) raises an error (channels` should be a directory).

According to Rails 4.2.2 - 5.0.0.1 diff the only channels directory is in app

So line 6, instead of

//= require_tree ./channels

I can only suppose should be

//= require_tree ../../channels

However I am not sure about this.

I wondering if anyone of you knows about what channels directory line 6 of cable.js is referring to.

Also, according to Cloud9 editor, ActionCable in app/assets/javascripts/cable.js results not defined: ActionCable is not defined; please fix or add /*global ActionCable*/

Did railsdiff.org/4.2.2/5.0.0.1 miss anything, like a channels directory in app/assets/javascripts or the definition somewhere of an ActionCable class?

On Fri, Aug 19, 2016 at 4:24 AM, 'krfg' via Ruby on Rails: Talk

I upgraded a copy of my rails 4.2.2 application to rails 5.0.0.1, following
instructions at railsapp and at edgeguides.rubyonrails.org
Most of my work consisted in consulting railsdiff.org, thus copying and
pasting new code to my application.

After completing all the necessary revisions and running tests, I was warned
about some issues.
Line 6 of app/assets/javascripts/cable.js (copied from railsdiff.org) raises
an error (channels should be a directory).

According to Rails 4.2.2 - 5.0.0.1 diff the only channels directory is in
app

So line 6, instead of

//= require_tree ./channels

I can only suppose should be

//= require_tree ../../channels

No.

If you generate a new Rails 5 app you'll see the directory in question
at app/assets/javascripts/channels.

Aside, I highly recommend `generate a new app` as an approach to
learning what's changed in any major update.

Generate it with the defaults, check in to git, check out a branch and
scaffold a channel or whatever - your git history now shows you what
got added/changed/deleted. And you have an example to compare
your upgraded app against.

FWIW,

Thanks.
Plainly railsdiff.org does not consider and report empty directories.
I found two of them:

app/assets/javascripts/channels/
test/fixtures/files/

with an hidden, empty .keep file inside each one

They are not in rails 4.2.2