Addressing Jon code-review on 4-0-dev

features/channel_specs/channel_spec.feature

@@ -4,11 +4,11 @@ Feature: channel spec
   Channel specs are marked by `:type => :channel` or if you have set
   `config.infer_spec_type_from_file_location!` by placing them in `spec/channels`.
 
-  A channel spec is a thin wrapper for an ActionCable::Channel::TestCase, and includes all
+  A channel spec is a thin wrapper for an `ActionCable::Channel::TestCase`, and includes all
   of the behavior and assertions that it provides, in addition to RSpec's own
   behavior and expectations.
 
-  It also includes helpers from ActionCable::Connection::TestCase to make it possible to
+  It also includes helpers from `ActionCable::Connection::TestCase` to make it possible to
   test connection behavior.
 
   Background:

lib/rspec/rails/configuration.rb

@@ -135,19 +135,19 @@ def filter_rails_from_backtrace!
         end
       end
 
-      if defined?(ActionMailer)
+      if RSpec::Rails::FeatureCheck.has_action_mailer?
         config.include RSpec::Rails::MailerExampleGroup, :type => :mailer
       end
 
-      if defined?(ActiveJob)
+      if RSpec::Rails::FeatureCheck.has_active_job?
         config.include RSpec::Rails::JobExampleGroup, :type => :job
       end
 
-      if defined?(ActionCable) && ::Rails::VERSION::STRING > '6'
+      if RSpec::Rails::FeatureCheck.has_action_cable_testing?
         config.include RSpec::Rails::ChannelExampleGroup, :type => :channel
       end
 
-      if defined?(ActionMailbox)
+      if RSpec::Rails::FeatureCheck.has_action_mailbox?
         config.include RSpec::Rails::MailboxExampleGroup, :type => :mailbox
       end
     end

lib/rspec/rails/example/channel_example_group.rb

@@ -15,7 +15,7 @@ module ClassMethods
   end
 end
 
-if ::Rails::VERSION::MAJOR >= 6
+if RSpec::Rails::FeatureCheck.has_action_cable_testing?
   module RSpec
     module Rails
       # @api public