LanguageFeatures/Spread-collections/Ambiguity_A01_t02.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 if [a] and [b] are map literals, their spread is a
 * map.
 * @author iarkh@unipro.ru
 */
// SharedOptions=--enable-experiment=constant-update-2018

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

main() {
  var map1 = {1: 1, "test": 1, 14: null};
  var map2 = <int, int>{10: 24};
  var map3 = <String, bool>{};
  var map4 = <bool, String>{true: "true", false: "false"};

  Map res1 = {...map1, ...map2};
  Expect.mapEquals({1: 1, "test": 1, 14: null, 10: 24}, res1);

  Map res2 = {...map2, ...map3};
  Expect.mapEquals({10: 24}, res2);

  Map res3 = {...map3, ...map4};
  Expect.mapEquals({true: "true", false: "false"}, res3);

  Map res4 = {...map1, ...map2, ...map3, ...map4};
  Expect.mapEquals(
      {1: 1, "test": 1, 14: null, 10: 24, true: "true", false: "false"}, res4);
}