// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// @dart = 2.9

/// @assertion K firstKey()
/// Returns [null] if the map is empty.
/// @description Checks that [null] is returned if map is empty
/// @author sgrekhov@unipro.ru

import "dart:collection";
import "../../../Utils/expect.dart";

main() {
  SplayTreeMap map = new SplayTreeMap();
  Expect.isNull(map.firstKey());
}