LibTest/typed_data/Int16List/expand_A02_t01.dart

// Copyright (c) 2017, 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 Iterable expand(Iterable f(E element))
/// ...
/// The returned Iterable is lazy, and calls f for each element of this every
/// time it's iterated.
/// @description Checks that the returned [Iterable] is lazy, and calls f for
/// each element of this every time it's iterated.
/// @author ngl@unipro.ru


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

main() {
  var l = new Int16List.fromList([1, 2, 3, 4]);
  var counter = 0;
  var res = l.expand((element) {counter++; return [element * 2];});
  var it = res.iterator;
  Expect.equals(0, counter);
  int i = 0;
  while (it.moveNext()) {
    Expect.equals(++i, counter);
  }
  Expect.equals(l.length, i);
}