LibTest/async/Stream/takeWhile_A01_t03.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 Stream<T> takeWhile(bool test(T element))
 * Forwards data events while test is successful.
 * The returned stream provides the same events as this stream as long as test
 * returns true for the event data.
 * The stream is done when either this stream is done, or when this stream first
 * provides a value that test doesn't accept.
 * @description Checks that if [test] throws an error, then the error is
 * emitted as an error event on the returned stream and it is considered as
 * [test] failure.
 * @author a.semenov@unipro.ru
 */
library takeWhile_A01_t03;
import "dart:async";
import "../../../Utils/expect.dart";

void check<T>(Stream<T> s, bool test(T element),
           Object expectedError, List<T> expected) {
  AsyncExpect.events(expected, [expectedError], s.takeWhile(test));
}

void test(CreateStreamFunction create) {
  AsyncExpect.data([], create([]).takeWhile((e) => throw "a"));
  check(create([1, 2, 3]), (e) => throw "b", "b", []);
  check<int>(
      create([-1, -2, -3, 1, 2, 3]),
      (element) {
        if (element > 0) {
          throw "c";
        };
        return true;
      },
      "c",
      [-1, -2, -3]
  );
}