Add StreamChannel.withGuarantees and StreamChannelController.

test/with_guarantees_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 'package:stream_channel/stream_channel.dart';
+import 'package:test/test.dart';
+
+import 'utils.dart';
+
+void main() {
+  var streamController;
+  var sinkController;
+  var channel;
+  setUp(() {
+    streamController = new StreamController();
+    sinkController = new StreamController();
+    channel = new StreamChannel.withGuarantees(
+        streamController.stream, sinkController.sink);
+  });
+
+  group("with a broadcast stream", () {
+    setUp(() {
+      streamController = new StreamController.broadcast();
+      channel = new StreamChannel.withGuarantees(
+          streamController.stream, sinkController.sink);
+    });
+
+    test("buffers events", () async {
+      streamController.add(1);
+      streamController.add(2);
+      streamController.add(3);
+      await pumpEventQueue();
+
+      expect(channel.stream.toList(), completion(equals([1, 2, 3])));
+      streamController.close();
+    });
+
+    test("only allows a single subscription", () {
+      channel.stream.listen(null);
+      expect(() => channel.stream.listen(null), throwsStateError);
+    });
+  });
+
+  test("closing the event sink causes the stream to close before it emits any "
+      "more events", () {
+    streamController.add(1);
+    streamController.add(2);
+    streamController.add(3);
+
+    expect(channel.stream.listen(expectAsync((event) {
+      if (event == 2) channel.sink.close();
+    }, count: 2)).asFuture(), completes);
+  });
+
+  test("after the stream closes, the sink ignores events", () async {
+    streamController.close();
+
+    // Wait for the done event to be delivered.
+    await channel.stream.toList();
+    channel.sink.add(1);
+    channel.sink.add(2);
+    channel.sink.add(3);
+    channel.sink.close();
+
+    // None of our channel.sink additions should make it to the other endpoint.
+    sinkController.stream.listen(
+        expectAsync((_) {}, count: 0),
+        onDone: expectAsync(() {}, count: 0));
+    await pumpEventQueue();
+  });
+
+  test("canceling 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);
+    channel.sink.close();
+    expect(sinkController.stream.toList(), completion(equals([1, 2, 3])));
+  });
+
+  test("canceling the stream's subscription doesn't stop a done event",
+      () async {
+    channel.stream.listen(null).cancel();
+    await pumpEventQueue();
+
+    streamController.close();
+    await pumpEventQueue();
+
+    channel.sink.add(1);
+    channel.sink.add(2);
+    channel.sink.add(3);
+    channel.sink.close();
+
+    // The sink should be ignoring events because the stream closed.
+    sinkController.stream.listen(
+        expectAsync((_) {}, count: 0),
+        onDone: expectAsync(() {}, count: 0));
+    await pumpEventQueue();
+  });
+
+  test("forwards errors to the other endpoint", () {
+    channel.sink.addError("error");
+    expect(sinkController.stream.first, throwsA("error"));
+  });
+}