LibTest/async/StreamTransformer/StreamTransformer.fromHandlers_A01_t03.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 factory StreamTransformer.fromHandlers({void handleData(S data,
 *   EventSink<T> sink), void handleError(Object error, StackTrace stackTrace,
 *   EventSink<T> sink), void handleDone(EventSink<T> sink)})
 * Creates a StreamTransformer that delegates events to the given functions.
 *
 * @description Checks that handleError() is called on error events and
 * transformed stream gets errors that are written to sink.
 * handleData is not provided, so data events are unchanged.
 * @author ilya
 */
import "dart:async";
import "../../../Utils/async_utils.dart";
import "../../../Utils/expect.dart";

main() {
  var s = new Stream.fromIterable([1,2,3,4,5]);
  
  // odd numbers as data events, even numbers as error events
  s = s.map((x) => x.isOdd ? x : throw x);

  var stackTraces = [];
  var tr = new StreamTransformer.fromHandlers(handleError: (x, st, sink) {
    stackTraces.add(st);
    sink.addError(x+10, st);
  });
  
  var data = 1;
  var error = 12;
  var error_count = 0;

  asyncStart();
  s.transform(tr).listen((x) {
    Expect.equals(data, x);
    data += 2;
  }, onError:(x, st) {
    Expect.equals(error, x);
    Expect.equals(stackTraces[error_count++], st);
    error += 2;
  }, onDone:() {
    asyncEnd();
  });
}