Language/Expressions/If_null_Expressions/static_type_t02.dart

// Copyright (c) 2015, 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.

/**
 * @assertion Evaluation of an if-null expression e of the form e1??e2 is
 * equivalent ... The static type of e is least upper bound of the
 * static type of e1 and the static type of e2 .
 *
 * @description Check that static type of expression e1 ?? e2 is least upper
 * bound of the static type of e1 and the static type of e2 .
 *
 * @author a.semenov@unipro.ru
 * @author sgrekhov@unipro.ru
 *
 */
import 'dart:collection';
import '../../../Utils/expect.dart';

main() {
  var d = 1.0 as double?;
  var x1 = d ?? 2.0;
  Expect.isTrue(x1 is double);

  var x2 = null ?? 2.0;
  Expect.isTrue(x2 is double);

  var s = 'aaa' as String?;
  var x3 = s ?? 'bbb';
  Expect.isTrue(x3 is String);

  var b = true as bool?;
  var x4 = b ?? false;
  Expect.isTrue(x4 is bool);

  var v = new LinkedHashMap() as LinkedHashMap?;
  var x5 = v ?? new SplayTreeMap();
  Expect.isTrue(x5 is LinkedHashMap);

  var x6 = s ?? null;
  Expect.isTrue(x6 is String);
}