// Copyright (c) 2017, 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 bool containsKey(Object key)
/// Returns [true] if this map contains the given [key].
/// Returns [true] if any of the keys in the map are equal to [key] according to
/// the equality used by the map.
/// @description Checks that [null] key is supported.
/// @author iarkh@unipro.ru

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

main() {
  UnmodifiableMapView view = new UnmodifiableMapView({});
  Expect.isFalse(view.containsKey(""));
  Expect.isFalse(view.containsKey(0));
  Expect.isFalse(view.containsKey(1));
  Expect.isFalse(view.containsKey(2));

  view = new UnmodifiableMapView({0 : 0, 1 : 4});
  Expect.isFalse(view.containsKey(""));
  Expect.isTrue(view.containsKey(0));
  Expect.isTrue(view.containsKey(1));
  Expect.isFalse(view.containsKey(2));
}