LibTest/async/Stream/singleWhere_A02_t01.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> singleWhere(bool test(T element))
 * Like lastMatch, except that it is an error if more than one matching element occurs in the stream.
 * @description Checks that it is an error if more than one matching element occurs in the stream.
 * @author kaigorodov
 */

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

void check(Iterable data, bool test(int element), var expected) {
  Stream s=new Stream.fromIterable(data);
  asyncStart();
  Future f=s.singleWhere(test);
  f.then(
    (var value){
      Expect.fail("unexpected call ot onValue($value)");
    },
    onError: (Object error){
      asyncEnd();
    }
  );
}

main() {
  check([1,2,3], (int element)=>true, 3);
  check([1,2,3], (int element)=>element!=null, 3);
  check([1,2,3], (int element)=>element>0, 3);
  check(new Iterable.generate(10, (int index)=>index*5), (int element)=>element!=30, 45);
}