LanguageFeatures/Spread-collections/StaticSemantic_A01_t05.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.

// @dart = 2.9

/// @assertion Since the spread is unpacked and its individual elements added to
/// the containing collection, we don't require the spread expression itself to
/// be assignable to the collection's type. For example, this is allowed:
///
///    var numbers = <num>[1, 2, 3];
///    var ints = <int>[...numbers];
///
/// This works because the individual elements in numbers do happen to have the
/// right type even though the list that contains them does not. As long as the
/// spread object is "spreadable" — it implements [Iterable] — there is no
/// static error.
/// @description Checks that it's possible to have the spread expression which is
/// not assignable to the collection type for the map.
/// @author iarkh@unipro.ru


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

main() {
  var numbers = <num, num>{1: 1, 2: 2, 3: 3};
  Expect.mapEquals({1: 1, 2: 2, 3: 3}, <int, int>{...numbers});

  var objects = <Object, Object>{2: 22, 7: 77, 9: 99};
  Expect.mapEquals({2: 22, 7: 77, 9: 99}, <int, int>{...objects});

  var a;
  Expect.throws(() => a = <String, int>{...objects});

  dynamic strings = <String>[];
  Expect.throws(() => a = <int, int>{11: 12, ...strings});


  numbers = <num, num>{1: 1, 2: 2, 3: 3};
  Expect.mapEquals({1: 1, 2: 2, 3: 3}, <int, int>{...?numbers});

  objects = <Object, Object>{2: 22, 7: 77, 9: 99};
  Expect.mapEquals({2: 22, 7: 77, 9: 99}, <int, int>{...?objects});

  Expect.throws(() => a = <String, int>{...?objects});

  strings = <String>[];
  Expect.throws(() => a = <int, int>{11: 12, ...?strings});

}