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);
}