Migrate async tests to strong

tests/lib_strong/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);
+  }
+}