LibTest/core/Iterable/takeWhile_A01_t01.test.dart

// Copyright (c) 2011, 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> takeWhile(bool test(E value))
/// Returns a lazy iterable of the leading elements satisfying test
/// @description Checks that all first elements that satisfy test are retained,
/// and elements after that, are skipped.
/// @author kaigorodov

library takeWhile_A01_t01;
import "../../../Utils/expect.dart"	;

void check(Iterable a0, bool tst(var element)) {
  Iterator it0 = a0.iterator;
  Iterable a = a0.takeWhile(tst);
  Iterator it = a.iterator;
  
  // check that the beginning of a0 is identical to a
  bool hasNext0 = it0.moveNext();
  int len = 0;
  for (;;) {
    bool hasNext = it.moveNext();
    if (!hasNext) break;
    Expect.isTrue(tst(it0.current));
    Expect.equals(it0.current, it.current);
    len++;
    hasNext0 = it0.moveNext();
  }
  Expect.equals(a.length, len);

  // count the rest
  int skipCount = 0;
  while (hasNext0) {
    skipCount++;
    hasNext0 = it0.moveNext();
  }
  Expect.equals(a0.length, len + skipCount);
}

test(Iterable create([Iterable content])) {
  Iterable a0 = create([1, 3, 7, 4, 5, 6]);
  check(a0, (var element) => element == 1);
  check(a0, (var element) => true);
  check(a0, (var element) => false);
  check(a0, (var element) => element > 4);
  check(a0, (var element) => element < 4);
  check(a0, (var element) => element == 4);
}