Make Webpacker the default JavaScript compiler for Rails 6 (#33079)

* Use Webpacker by default on new apps

* Stop including coffee-rails by default

* Drop using a js_compressor by default

* Drop extra test for coffeescript inclusion by default

* Stick with skip_javascript to signify skipping webpack

* Don't install a JS runtime by default any more

* app/javascript will be the new default directory for JS

* Make it clear that this is just for configuring the default Webpack framework setup now

* Start using the Webpack tag in the default layout

* Irrelevant test

* jQuery is long gone

* Stop having asset pipeline compile default application.js

* Add rails-ujs by default to the Webpack setup

* Add Active Storage JavaScript to application.js pack by default

* Consistent quoting

* Add Turbolinks to default pack

* Add Action Cable to default pack

Need some work on how to set the global consumer that channels will
work with. @javan?

* Require all channels by default and use a separate consumer stub

* Channel generator now targets Webpack style

* Update task docs to match new generator style

* Use uniform import style

* Drop the JS assets generator

It was barely helpful as it was. It’s no longer helpful in a Webpacked
world. Sayonara!

* Add app/javascript to the stats directories

* Simpler import style

Which match the other imports.

* Address test failures from dropping JS compilation (and compression)

* webpacker-default: Modify `AssetsGeneratorTest`

Before:

```
$ bin/test test/generators/assets_generator_test.rb
Run options: --seed 46201

F

Failure:
AssetsGeneratorTest#test_assets [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/assets_generator_test.rb:12]:
Expected file "app/assets/javascripts/posts.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/assets_generator_test.rb:10

.

Finished in 0.031343s, 63.8101 runs/s, 95.7152 assertions/s.
2 runs, 3 assertions, 1 failures, 0 errors, 0 skips
```

After:

```
$ bin/test test/generators/assets_generator_test.rb
Run options: --seed 43571

..

Finished in 0.030370s, 65.8545 runs/s, 65.8545 assertions/s.
2 runs, 2 assertions, 0 failures, 0 errors, 0 skips
```

* webpacker-default: Modify `ChannelGeneratorTest`

Before:

```
$ bin/test test/generators/channel_generator_test.rb
Run options: --seed 8986

.F

Failure:
ChannelGeneratorTest#test_channel_with_multiple_actions_is_created [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:43]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:34

.F

Failure:
ChannelGeneratorTest#test_channel_is_created [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:29]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:22

E

Error:
ChannelGeneratorTest#test_cable_js_is_created_if_not_present_already:
Errno::ENOENT: No such file or directory @ apply2files - /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/fixtures/tmp/app/assets/javascripts/cable.js

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:60

F

Failure:
ChannelGeneratorTest#test_channel_suffix_is_not_duplicated [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:87]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:80

F

Failure:
ChannelGeneratorTest#test_channel_on_revoke [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:77]:
Expected file "app/assets/javascripts/cable.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:68

Finished in 0.064384s, 108.7227 runs/s, 481.4861 assertions/s.
7 runs, 31 assertions, 4 failures, 1 errors, 0 skips
```

After:

```
$ bin/test test/generators/channel_generator_test.rb
Run options: --seed 44857

.......

Finished in 0.060243s, 116.1961 runs/s, 697.1764 assertions/s.
7 runs, 42 assertions, 0 failures, 0 errors, 0 skips
```

* Fix shared generator tests.

* webpacker-default: Modify `ControllerGeneratorTest`

The JS assets generator was dropped. ref. https://github.com/rails/rails/commit/46215b179483d3e4d264555f5a4952f43eb8142a

* Revert "Simpler import style". It's currently failing with an error of "TypeError: undefined is not an object (evaluating '__WEBPACK_IMPORTED_MODULE_2_activestorage___default.a.start')". Waiting for @javan to have a look.

This reverts commit 5d3ebb71059f635d3756cbda4ab9752027e09256.

* require webpacker in test app

* Add webpacker without making the build hang/timeout. (#33640)

* use yarn workspaces to allow for installing unreleased packages and only generate js/bootsnap when required

* no longer need to have webpacker in env templates as webpacker moved this config to yml file

* Fix rubocop violation

* Got the test passing for the running scaffold

* update expected lines of code

* update middleware tests to account for webpacker

* disable js in plugins be default to get the tests passing (#34009)

* clear codeclimate report issues

* Anything newer than currently released is good

* Use Webpacker development version during development of Rails

* Edge should get development webpacker as well

* Add changelog entry for Webpacker change

6 files changed, 16 insertions, 31 deletions

diff --git a/actioncable/lib/rails/generators/channel/USAGE b/actioncable/lib/rails/generators/channel/USAGE
index dd109fda80..ea9662436c 100644
--- a/actioncable/lib/rails/generators/channel/USAGE
+++ b/actioncable/lib/rails/generators/channel/USAGE
@@ -1,14 +1,12 @@
 Description:
 ============
-    Stubs out a new cable channel for the server (in Ruby) and client (in CoffeeScript).
+    Stubs out a new cable channel for the server (in Ruby) and client (in JavaScript).
     Pass the channel name, either CamelCased or under_scored, and an optional list of channel actions as arguments.
 
-    Note: Turn on the cable connection in app/assets/javascripts/cable.js after generating any channels.
-
 Example:
 ========
     rails generate channel Chat speak
 
-    creates a Chat channel class and CoffeeScript asset:
+    creates a Chat channel class and JavaScript asset:
         Channel:    app/channels/chat_channel.rb
-        Assets:     app/assets/javascripts/channels/chat.coffee
+        Assets:     app/javascript/channels/chat_channel.js
diff --git a/actioncable/lib/rails/generators/channel/channel_generator.rb b/actioncable/lib/rails/generators/channel/channel_generator.rb
index 427eef1f55..ef51981e89 100644
--- a/actioncable/lib/rails/generators/channel/channel_generator.rb
+++ b/actioncable/lib/rails/generators/channel/channel_generator.rb
@@ -16,10 +16,11 @@ module Rails
 
         if options[:assets]
           if behavior == :invoke
-            template "assets/cable.js", "app/assets/javascripts/cable.js"
+            template "javascript/index.js", "app/javascript/channels/index.js"
+            template "javascript/consumer.js", "app/javascript/channels/consumer.js"
           end
 
-          js_template "assets/channel", File.join("app/assets/javascripts/channels", class_path, "#{file_name}")
+          js_template "javascript/channel", File.join("app/javascript/channels", class_path, "#{file_name}_channel")
         end
 
         generate_application_cable_files
diff --git a/actioncable/lib/rails/generators/channel/templates/assets/channel.coffee.tt b/actioncable/lib/rails/generators/channel/templates/assets/channel.coffee.tt
deleted file mode 100644
index 5467811aba..0000000000
--- a/actioncable/lib/rails/generators/channel/templates/assets/channel.coffee.tt
+++ /dev/null
@@ -1,14 +0,0 @@
-App.<%= class_name.underscore %> = App.cable.subscriptions.create "<%= class_name %>Channel",
-  connected: ->
-    # Called when the subscription is ready for use on the server
-
-  disconnected: ->
-    # Called when the subscription has been terminated by the server
-
-  received: (data) ->
-    # Called when there's incoming data on the websocket for this channel
-<% actions.each do |action| -%>
-
-  <%= action %>: ->
-    @perform '<%= action %>'
-<% end -%>
diff --git a/actioncable/lib/rails/generators/channel/templates/assets/channel.js.tt b/actioncable/lib/rails/generators/channel/templates/javascript/channel.js.tt
index ab0e68b11a..33baaa5a22 100644
--- a/actioncable/lib/rails/generators/channel/templates/assets/channel.js.tt
+++ b/actioncable/lib/rails/generators/channel/templates/javascript/channel.js.tt
@@ -1,4 +1,6 @@
-App.<%= class_name.underscore %> = App.cable.subscriptions.create("<%= class_name %>Channel", {
+import consumer from "./consumer"
+
+consumer.subscriptions.create("<%= class_name %>Channel", {
   connected: function() {
     // Called when the subscription is ready for use on the server
   },
diff --git a/actioncable/lib/rails/generators/channel/templates/assets/cable.js.tt b/actioncable/lib/rails/generators/channel/templates/javascript/consumer.js.tt
index 739aa5f022..76ca3d0f2f 100644
--- a/actioncable/lib/rails/generators/channel/templates/assets/cable.js.tt
+++ b/actioncable/lib/rails/generators/channel/templates/javascript/consumer.js.tt
@@ -1,13 +1,6 @@
 // Action Cable provides the framework to deal with WebSockets in Rails.
 // You can generate new channels where WebSocket features live using the `rails generate channel` command.
-//
-//= require action_cable
-//= require_self
-//= require_tree ./channels
 
-(function() {
-  this.App || (this.App = {});
+import ActionCable from "actioncable"
 
-  App.cable = ActionCable.createConsumer();
-
-}).call(this);
+export default ActionCable.createConsumer()
diff --git a/actioncable/lib/rails/generators/channel/templates/javascript/index.js.tt b/actioncable/lib/rails/generators/channel/templates/javascript/index.js.tt
new file mode 100644
index 0000000000..5da1ce2dce
--- /dev/null
+++ b/actioncable/lib/rails/generators/channel/templates/javascript/index.js.tt
@@ -0,0 +1,5 @@
+// Load all the channels within this directory and all subdirectories. 
+// Channel files must be named *_channel.js.
+
+const channels = require.context('.', true, /\_channel\.js$/)
+channels.keys().forEach(channels)