pkg/front_end/testcases/patterns/issue51489.dart

// Copyright (c) 2023, 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.

test1() => <dynamic, dynamic>{for (var [i] in []) i: i};

test2(dynamic x, dynamic another) => {
  1: 1,
  for (var [i] in x)
    for (var [j] in x) ...another,
};

main() {
  expectEquals(mapToString(test1()), mapToString({}));
  expectEquals(mapToString(test2([], {2: 2})), mapToString({1: 1}));
  expectEquals(
    mapToString(
      test2(
        [
          [0],
          [1],
          [2],
        ],
        {2: 2},
      ),
    ),
    mapToString({1: 1, 2: 2}),
  );
}

expectEquals(x, y) {
  if (x != y) {
    throw "Expected '${x}' to be equal to '${y}'.";
  }
}

mapToString(Map map) {
  List<String> entryStrings = [
    for (var e in map.entries) "${e.key}:${e.value}",
  ];
  entryStrings.sort();
  return "{${entryStrings.join(',')}}";
}