Add channel test generator

actioncable/lib/rails/generators/channel/USAGE

@@ -7,6 +7,7 @@ Example:
 ========
     rails generate channel Chat speak
 
-    creates a Chat channel class and JavaScript asset:
+    creates a Chat channel class, test and JavaScript asset:
         Channel:    app/channels/chat_channel.rb
+        Test:       test/channels/chat_channel_test.rb
         Assets:     app/javascript/channels/chat_channel.js

actioncable/lib/rails/generators/channel/channel_generator.rb

@@ -11,6 +11,8 @@ module Rails
 
       check_class_collision suffix: "Channel"
 
+      hook_for :test_framework
+
       def create_channel_file
         template "channel.rb", File.join("app/channels", class_path, "#{file_name}_channel.rb")
 

actioncable/lib/rails/generators/test_unit/channel_generator.rb

@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+module TestUnit
+  module Generators
+    class ChannelGenerator < ::Rails::Generators::NamedBase
+      source_root File.expand_path("templates", __dir__)
+
+      check_class_collision suffix: "ChannelTest"
+
+      def create_test_files
+        template "channel_test.rb", File.join("test/channels", class_path, "#{file_name}_channel_test.rb")
+      end
+
+      private
+        def file_name # :doc:
+          @_file_name ||= super.sub(/_channel\z/i, "")
+        end
+    end
+  end
+end

actioncable/lib/rails/generators/test_unit/templates/channel_test.rb.tt

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+class <%= class_name %>ChannelTest < ActionCable::Channel::TestCase
+  # test "subscribes" do
+  #   subscribe
+  #   assert subscription.confirmed?
+  # end
+end

railties/test/generators/channel_generator_test.rb

@@ -67,12 +67,23 @@ class ChannelGeneratorTest < Rails::Generators::TestCase
     assert_file "app/javascript/channels/consumer.js"
   end
 
+  def test_invokes_default_test_framework
+    run_generator %w(chat -t=test_unit)
+
+    assert_file "test/channels/chat_channel_test.rb" do |test|
+      assert_match(/class ChatChannelTest < ActionCable::Channel::TestCase/, test)
+      assert_match(/# test "subscribes" do/, test)
+      assert_match(/#   assert subscription.confirmed\?/, test)
+    end
+  end
+
   def test_channel_on_revoke
     run_generator ["chat"]
     run_generator ["chat"], behavior: :revoke
 
     assert_no_file "app/channels/chat_channel.rb"
     assert_no_file "app/javascript/channels/chat_channel.js"
+    assert_no_file "test/channels/chat_channel_test.rb"
 
     assert_file "app/channels/application_cable/channel.rb"
     assert_file "app/channels/application_cable/connection.rb"
@@ -88,5 +99,8 @@ class ChannelGeneratorTest < Rails::Generators::TestCase
 
     assert_no_file "app/javascript/channels/chat_channel_channel.js"
     assert_file "app/javascript/channels/chat_channel.js"
+
+    assert_no_file "test/channels/chat_channel_channel_test.rb"
+    assert_file "test/channels/chat_channel_test.rb"
   end
 end