anchor.diff:      insert_and_find,
       insert_and_delete,
       search_and_query,
  -    update
  +    update,
  +    sort_and_limit
     ].
   
   init_per_suite(Config) ->
  
positive.code:   insert_and_find/1,
    insert_and_delete/1,
    search_and_query/1,
    update/1
  ]).
  
  all() ->
  
negative.code:     {'_id', _,
        name, <<"Mets">>,
        league, <<"National">>}] = Res2,
    Config.
  
  sort_and_limit(Config) ->
    Connection = ?config(connection, Config),
    Collection = ?config(collection, Config),
  
    %insert test data
    mongo:insert(Connection, Collection, [
      {key, <<"test">>, value, <<"two">>, tag, 2},
      {key, <<"test">>, value, <<"one">>, tag, 1},
      {key, <<"test">>, value, <<"four">>, tag, 4},
      {key, <<"another">>, value, <<"five">>, tag, 5},
      {key, <<"test">>, value, <<"three">>, tag, 3}
    ]),
  
    %test match and sort
    {true, {result, Res}} = mongo:command(Connection, {aggregate, <<"test">>, pipeline, [{'$match', {key, <<"test">>}}, {'$sort', {tag, 1}}]}),
    ?debugFmt("Got ~p", [Res]),
    [
      {'_id', _, key, <<"test">>, value, <<"one">>, tag, 1},
      {'_id', _, key, <<"test">>, value, <<"two">>, tag, 2},
      {'_id', _, key, <<"test">>, value, <<"three">>, tag, 3},
      {'_id', _, key, <<"test">>, value, <<"four">>, tag, 4}
    ] = Res,
  
    %test match & sort with limit
    {true, {result, Res1}} = mongo:command(Connection,
      {aggregate, <<"test">>, pipeline,
        [
          {'$match', {key, <<"test">>}},
          {'$sort', {tag, 1}},
          {'$limit', 1}
        ]}),
    ?debugFmt("Got ~p", [Res1]),
    [
      {'_id', _, key, <<"test">>, value, <<"one">>, tag, 1}
    ] = Res1,
    Config.
  
  update(Config) ->
  