Extend list of Rails spec types for DescribeClass

There are more: https://github.com/rspec/rspec-rails/blob/56aed229410a8e7a30743d82b8770596fd8c125c/lib/rspec/rails/configuration.rb#L28

Author: pirj

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Master (Unreleased)
 
+* Extend the list of Rails spec types for `RSpec/DescribeClass`. ([@pirj][])
+
 ## 1.40.0 (2020-06-11)
 
 * Add new `RSpec/VariableName` cop. ([@tejasbubane][])

lib/rubocop/cop/rspec/describe_class.rb

@@ -43,7 +43,11 @@ class DescribeClass < Cop
         def_node_matcher :rails_metadata?, <<-PATTERN
           (pair
             (sym :type)
-            (sym {:request :feature :system :routing :view})
+            (sym {
+                   :channel :controller :helper :job :mailer :model :request
+                   :routing :view :feature :system :mailbox
+                 }
+            )
           )
         PATTERN