LibTest/collection/IterableMixin/take_A01_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.

/// @assertion Iterable<E> take(int count)
/// Returns a lazy iterable of the [count] first elements of this iterable.
/// @description Checks that [Iterable] that contains the first [count] elements
/// is returned.
/// @author iarkh@unipro.ru

import "dart:collection";
import "dart:math" as Math;
import "../../../Utils/expect.dart";

class MyIterable<int> extends Object with IterableMixin {
  List _content;
  MyIterable(List list): _content = list;

  Iterator get iterator {
    return _content.iterator;
  }
}

check(List list, int n) {
  IterableMixin iterable = new MyIterable(list);
  Iterable res = iterable.take(n);
  Expect.equals(Math.min(iterable.length, n), res.length);
  int k = 0;
  for (var el in res) {
    Expect.equals(iterable.elementAt(k), el);
    k++;
  }      
}

main() {
  check([1, 2, -3, 4], 4);
  check([1, 2, -3, 4], 0);
  check([11, 2, -3, 4], 2);
  check([1, 22, -3, 4], 4);
  check(const[1, 2, -5, -6, 100], 0);
  check(const[1, -1, 2, -5, -6], 1);
  check(const[0, 0, 1, 2, -5, -6], 2);
  check(const[0, 0, 1, 2, -5, -6], 6);
}