LanguageFeatures/Spread-collections/Ambiguity_A01_t07.dart

/*
 * Copyright (c) 2019, 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 An expression like:
 *  { ...a, ...b }
 * Is syntactically parsed as [mapOrSetLiteral]. To determine whether it
 * actually is a map or set, the surrounding context is used. Given an
 * [mapOrSetLiteral] with context type [C]:
 *
 * If [Set<Null>] is assignable to [C], and [Map<Null, Null>] is not
 * assignable to [C], then the collection is a set literal.
 *
 * Otherwise, it is a map literal.
 *
 *  In other words, if it can only be a set, it is. Otherwise, it's a map.
 * @description Checks that given expression works if some ot the spread
 * elements is [null].
 * @author iarkh@unipro.ru
 */

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

main() {
  List list =  [1, 12, 24];
  Map map = {1: 1, "test": 1, 14: null};

  Set res1 = {...list, ...?null};
  Expect.setEquals({1, 12, 24}, res1);

  Set res2 = {...?null, ...list};
  Expect.setEquals({1, 12, 24}, res2);

  Map res3 = {...?null, ...map};
  Expect.mapEquals(map, res3);

  Map res4 = {...map, ...?null};
  Expect.mapEquals(map, res4);
}