LanguageFeatures/Spread-collections/ConstSpreads_A07_t01.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 It also enables const expressions that refer to constant
/// collections defined elsewhere, which is useful:
///   const list = [2, 3];
///   const another = [1, ...list, 4]; // [1, 2, 3, 4].
/// @description: Checks that spread element in the list can refer to constant
/// collections defined elsewhere
/// @author iarkh@unipro.ru

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

const List list = [2, 3];
const list1 = null;
const Set set = {2, 3};

main() {
  const res1 = [1, ...list, 4];
  Expect.listEquals([1, 2, 3, 4], res1);
  const res2 = [1, ...?list, 4];
//                 ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                     ^
// [cfe] Operand of null-aware operation '...?' has type 'List<dynamic>' which excludes null.
  Expect.listEquals([1, 2, 3, 4], res2);
  const res3 = [1, ...?list1, 4];
  Expect.listEquals([1, 4], res3);

  const res4 = [1, ...set, 4];
  Expect.listEquals([1, 2, 3, 4], res4);
  const res5 = [1, ...?set, 4];
//                 ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                     ^
// [cfe] Operand of null-aware operation '...?' has type 'Set<dynamic>' which excludes null.
  Expect.listEquals([1, 2, 3, 4], res5);
}