anchor.diff:          , malformed_request/2
           , allowed_methods/2
           , resource_exists/2
  +        , delete_resource/2
           , content_types_provided/2
           , to_json/2
           , process_post/2
  
positive.code:               {Methods, _, _} = allowed_methods(req, state),
                ?assert(lists:member('GET', Methods)),
                ?assert(lists:member('POST', Methods)),
                ?assert(lists:member('HEAD', Methods)),
                ?assertEqual(3, erlang:length(Methods)),
                ok
        end
      ].
  
negative.code:     {false, Req, State}.
  
  allowed_methods(Req, State) ->
      {['GET', 'POST', 'DELETE', 'HEAD'], Req, State}.
  
  resource_exists(Req, State = #state{mode = collection}) ->
      {true, Req, State};
  