Add `include_module` matcher

spec/support/matchers.rb

@@ -28,6 +28,16 @@ RSpec::Matchers.define :be_404_for do |user|
   end
 end
 
+RSpec::Matchers.define :include_module do |expected|
+  match do
+    described_class.included_modules.include?(expected)
+  end
+
+  failure_message_for_should do
+    "expected #{described_class} to include the #{expected} module"
+  end
+end
+
 module UrlAccess
   def url_allowed?(user, url)
     emulate_user(user)