Simplify testing array contents

We were testing for the size and the content of the elements when we
could test for the array itself.

spec/models/comment_spec.rb

@@ -131,8 +131,7 @@ describe Comment do
       create(:comment, administrator_id: create(:administrator).id)
       create(:comment, moderator_id: create(:moderator).id)
 
-      expect(Comment.not_as_admin_or_moderator.size).to eq(1)
-      expect(Comment.not_as_admin_or_moderator.first).to eq(comment1)
+      expect(Comment.not_as_admin_or_moderator).to eq [comment1]
     end
   end