Add an IsolateChannel class.

test/isolate_channel_test.dart

+// Copyright (c) 2016, 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.
+
+import 'dart:async';
+import 'dart:isolate';
+
+import 'package:stream_channel/stream_channel.dart';
+import 'package:test/test.dart';
+
+import 'utils.dart';
+
+void main() {
+  var receivePort;
+  var sendPort;
+  var channel;
+  setUp(() {
+    receivePort = new ReceivePort();
+    var receivePortForSend = new ReceivePort();
+    sendPort = receivePortForSend.sendPort;
+    channel = new IsolateChannel(receivePortForSend, receivePort.sendPort);
+  });
+
+  tearDown(() {
+    receivePort.close();
+    channel.sink.close();
+  });
+
+  test("the channel can send messages", () {
+    channel.sink.add(1);
+    channel.sink.add(2);
+    channel.sink.add(3);
+
+    expect(receivePort.take(3).toList(), completion(equals([1, 2, 3])));
+  });
+
+  test("the channel can receive messages", () {
+    sendPort.send(1);
+    sendPort.send(2);
+    sendPort.send(3);
+
+    expect(channel.stream.take(3).toList(), completion(equals([1, 2, 3])));
+  });
+
+  test("events can't be added to an explicitly-closed sink", () {
+    expect(channel.sink.close(), completes);
+    expect(() => channel.sink.add(1), throwsStateError);
+    expect(() => channel.sink.addError("oh no"), throwsStateError);
+    expect(() => channel.sink.addStream(new Stream.fromIterable([])),
+        throwsStateError);
+  });
+
+  test("events can't be added while a stream is being added", () {
+    var controller = new StreamController();
+    channel.sink.addStream(controller.stream);
+
+    expect(() => channel.sink.add(1), throwsStateError);
+    expect(() => channel.sink.addError("oh no"), throwsStateError);
+    expect(() => channel.sink.addStream(new Stream.fromIterable([])),
+        throwsStateError);
+    expect(() => channel.sink.close(), throwsStateError);
+
+    controller.close();
+  });
+
+  group("stream channel rules", () {
+    test("closing the sink causes the stream to close before it emits any more "
+        "events", () {
+      sendPort.send(1);
+      sendPort.send(2);
+      sendPort.send(3);
+      sendPort.send(4);
+      sendPort.send(5);
+
+      channel.stream.listen(expectAsync((message) {
+        expect(message, equals(1));
+        channel.sink.close();
+      }, count: 1));
+    });
+
+    test("cancelling the stream's subscription has no effect on the sink",
+        () async {
+      channel.stream.listen(null).cancel();
+      await pumpEventQueue();
+
+      channel.sink.add(1);
+      channel.sink.add(2);
+      channel.sink.add(3);
+      expect(receivePort.take(3).toList(), completion(equals([1, 2, 3])));
+    });
+
+    test("the sink closes as soon as an error is added", () async {
+      channel.sink.addError("oh no");
+      channel.sink.add(1);
+      expect(channel.sink.done, throwsA("oh no"));
+
+      // Since the sink is closed, the stream should also be closed.
+      expect(channel.stream.isEmpty, completion(isTrue));
+
+      // The other end shouldn't receive the next event, since the sink was
+      // closed. Pump the event queue to give it a chance to.
+      receivePort.listen(expectAsync((_) {}, count: 0));
+      await pumpEventQueue();
+    });
+
+    test("the sink closes as soon as an error is added via addStream",
+        () async {
+      var canceled = false;
+      var controller = new StreamController(onCancel: () {
+        canceled = true;
+      });
+
+      // This future shouldn't get the error, because it's sent to [Sink.done].
+      expect(channel.sink.addStream(controller.stream), completes);
+
+      controller.addError("oh no");
+      expect(channel.sink.done, throwsA("oh no"));
+      await pumpEventQueue();
+      expect(canceled, isTrue);
+
+      // Even though the sink is closed, this shouldn't throw an error because
+      // the user didn't explicitly close it.
+      channel.sink.add(1);
+    });
+  });
+}