LibTest/async/Stream/reduce_A03_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 Future<T> reduce(T combine(T previous, T element))
/// Reduces a sequence of values by repeatedly applying combine.
/// @description Checks that if stream contains error, then returned future is
/// completed with this error.
/// @author a.semenov@unipro.ru

library reduce_A03_t01;

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

void check<T>(Stream<T> s, T combine(T p, T e), Object expected) {
  AsyncExpect.error(expected, s.reduce(combine));
}

void test(CreateStreamWithErrorsFunction create) {
  check(create([1, 2, 3, 4, 5], isError: (_) => true, defVal: 42),
      (int p, int e) => p + e, 1);
  check<int>(create([1, 2, 3, 4, 5], isError: (x) => x.isEven, defVal: 42),
      (int p, int e) => p * e, 2);
  check(create([1, 2, 3, 4, 5], isError: (x) => x == 5, defVal: 42),
      (int p, int e) => p + e, 5);
}