pkg/front_end/testcases/patterns/simple_pattern_for_in.dart

// Copyright (c) 2025, 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 x) {
  for (var [int y] in x) {
    if (y % 10 == 0) {
      return y;
    }
  }
  return -1;
}

test2(Iterable<List<String>> x) {
  for (var [..., String y] in x) {
    if (y.startsWith("f")) {
      return y;
    }
  }
  return "";
}

test3(Iterable<dynamic> x) {
  for (var [int y, ...] in x) {
    return y;
  }
  return -1;
}

main() {
  expectEquals(
    test1([
      [1],
      [2],
      [3],
    ]),
    -1,
  );
  expectEquals(
    test1([
      [1],
      [2],
      [30],
    ]),
    30,
  );
  expectEquals(
    test2([
      ["foo", "bar", "baz"],
      ["bar", "foo", "baz"],
      ["bar", "baz", "foo"],
    ]),
    "foo",
  );
  expectEquals(test2([]), "");
  expectThrows(
    () => test3([
      [null, 1, 2],
    ]),
  );
  expectEquals(test3([]), -1);
}

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

expectThrows(void Function() f) {
  bool hasThrown = true;
  try {
    f();
    hasThrown = false;
  } catch (e) {}
  if (!hasThrown) {
    throw "Expected function to throw.";
  }
}