Migrated test block 168 to Dart 2.0.

tests/lib/async/event_helper.dart

-// Copyright (c) 2012, 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.
-
-library event_helper;
-
-import 'dart:async';
-
-abstract class Event {
-  void replay(EventSink sink);
-}
-
-class DataEvent implements Event {
-  final data;
-
-  DataEvent(this.data);
-
-  void replay(EventSink sink) {
-    sink.add(data);
-  }
-
-  int get hashCode => data.hashCode;
-
-  bool operator ==(Object other) {
-    if (other is! DataEvent) return false;
-    DataEvent otherEvent = other;
-    return data == otherEvent.data;
-  }
-
-  String toString() => "DataEvent: $data";
-}
-
-class ErrorEvent implements Event {
-  final error;
-
-  ErrorEvent(this.error);
-
-  void replay(EventSink sink) {
-    sink.addError(error);
-  }
-
-  int get hashCode => error.error.hashCode;
-
-  bool operator ==(Object other) {
-    if (other is! ErrorEvent) return false;
-    ErrorEvent otherEvent = other;
-    return error == otherEvent.error;
-  }
-
-  String toString() => "ErrorEvent: ${error}";
-}
-
-class DoneEvent implements Event {
-  const DoneEvent();
-
-  void replay(EventSink sink) {
-    sink.close();
-  }
-
-  int get hashCode => 42;
-
-  bool operator ==(Object other) => other is DoneEvent;
-
-  String toString() => "DoneEvent";
-}
-
-/** Collector of events. */
-class Events implements EventSink {
-  final List<Event> events = [];
-  bool trace = false;
-  Completer onDoneSignal = new Completer();
-
-  Events();
-
-  Events.fromIterable(Iterable iterable) {
-    for (var value in iterable) add(value);
-    close();
-  }
-
-  /** Capture events from a stream into a new [Events] object. */
-  factory Events.capture(Stream stream, {bool cancelOnError}) = CaptureEvents;
-
-  // EventSink interface.
-  void add(var value) {
-    if (trace) print("Events#$hashCode: add($value)");
-    events.add(new DataEvent(value));
-  }
-
-  void addError(error, [StackTrace stackTrace]) {
-    if (trace) print("Events#$hashCode: addError($error)");
-    events.add(new ErrorEvent(error));
-  }
-
-  void close() {
-    if (trace) print("Events#$hashCode: close()");
-    events.add(const DoneEvent());
-    onDoneSignal.complete();
-  }
-
-  /**
-   * Error shorthand, for writing events manually.
-   */
-  void error(var value, [StackTrace stackTrace]) {
-    addError(value, stackTrace);
-  }
-
-  /** Replay the captured events on a sink. */
-  void replay(EventSink sink) {
-    for (int i = 0; i < events.length; i++) {
-      events[i].replay(sink);
-    }
-  }
-
-  /**
-   * Create a new [Events] with the same captured events.
-   *
-   * This does not copy a subscription.
-   */
-  Events copy() {
-    Events result = new Events();
-    replay(result);
-    return result;
-  }
-
-  // Operations that only work when there is a subscription feeding the Events.
-
-  /**
-   * Pauses the subscription that feeds this [Events].
-   *
-   * Should only be used when there is a subscription. That is, after a
-   * call to [subscribeTo].
-   */
-  void pause([Future resumeSignal]) {
-    throw new StateError("Not capturing events.");
-  }
-
-  /** Resumes after a call to [pause]. */
-  void resume() {
-    throw new StateError("Not capturing events.");
-  }
-
-  /**
-   * Sets an action to be called when this [Events] receives a 'done' event.
-   *
-   * The action will also be called if capturing events from a stream with
-   * `cancelOnError` set to true and receiving an error.
-   */
-  void onDone(void action()) {
-    onDoneSignal.future.whenComplete(action);
-  }
-}
-
-class CaptureEvents extends Events {
-  StreamSubscription subscription;
-  bool cancelOnError = false;
-
-  CaptureEvents(Stream stream, {bool cancelOnError: false}) {
-    this.cancelOnError = cancelOnError;
-    subscription = stream.listen(add,
-        onError: addError, onDone: close, cancelOnError: cancelOnError);
-  }
-
-  void addError(error, [stackTrace]) {
-    super.addError(error, stackTrace);
-    if (cancelOnError) {
-      onDoneSignal.complete();
-    }
-  }
-
-  void pause([Future resumeSignal]) {
-    if (trace) print("Events#$hashCode: pause");
-    subscription.pause(resumeSignal);
-  }
-
-  void resume() {
-    if (trace) print("Events#$hashCode: resume");
-    subscription.resume();
-  }
-
-  void onDone(void action()) {
-    if (trace) print("Events#$hashCode: onDone");
-    super.onDone(action);
-  }
-}