Add missing test

test/models/concerns/mentions_test.rb

@@ -12,4 +12,11 @@ class MentionsTest < ActiveSupport::TestCase
       end
     end
   end
+
+  test "mentionees are added as watchers of the card" do
+    perform_enqueued_jobs only: Mention::CreateJob do
+      card = collections(:writebook).cards.create title: "Cleanup", description: "Did you finish up with the cleanup @kevin?"
+      assert card.watchers.include?(users(:kevin))
+    end
+  end
 end