LibTest/core/Runes/map_A02_t01.dart

// Copyright (c) 2013, 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 Iterable map(f(E element))
 * As long as the returned [Iterable] is not iterated over,
 * the supplied function [f] will not be invoked.
 * @description Checks that [f] will not be invoked until
 * the returned [Iterable] is not iterated over.
 * @author msyabro
 */
import "../../../Utils/expect.dart";

main() {
  bool invoked = false;
  f(e) {
    invoked = true;;
    return e;
  }

  var runes = new Runes('_');
  var res = runes.map(f);

  Expect.isFalse(invoked);
  res.elementAt(0);
  Expect.isTrue(invoked);
}