Add new features to package:async.

test/subscription_stream_test.dart

+// Copyright (c) 2015, 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:async/async.dart" show SubscriptionStream;
+import "package:test/test.dart";
+
+main() {
+  test("subscription stream of an entire subscription", () async {
+    var stream = createStream();
+    var subscription = stream.listen(null);
+    var subscriptionStream = new SubscriptionStream<int>(subscription);
+    await flushMicrotasks();
+    expect(subscriptionStream.toList(), completion([1, 2, 3, 4]));
+  });
+
+  test("subscription stream after two events", () async {
+    var stream = createStream();
+    int skips = 0;
+    var c = new Completer();
+    var sub;
+    sub = stream.listen((v) {
+      ++skips;
+      expect(v, skips);
+      if (skips == 2) c.complete(new SubscriptionStream<int>(sub));
+    });
+    Stream<int> ss = await c.future;
+    await flushMicrotasks();
+    expect(ss.toList(), completion([3, 4]));
+  });
+
+  test("listening twice fails", () async {
+    var stream = createStream();
+    var sourceSubscription = stream.listen(null);
+    var subscriptionStream = new SubscriptionStream<int>(sourceSubscription);
+    var subscription = subscriptionStream.listen(null);
+    expect(() => subscriptionStream.listen(null), throws);
+    await subscription.cancel();
+  });
+
+  test("pause and cancel passed through to original stream", () async {
+    var controller = new StreamController(onCancel: () async => 42);
+    var sourceSubscription = controller.stream.listen(null);
+    var subscriptionStream = new SubscriptionStream(sourceSubscription);
+    expect(controller.isPaused, isTrue);
+    var lastEvent;
+    var subscription = subscriptionStream.listen((v) { lastEvent = v; });
+    controller.add(1);
+    await flushMicrotasks();
+    expect(lastEvent, 1);
+    expect(controller.isPaused, isFalse);
+    subscription.pause();
+    expect(controller.isPaused, isTrue);
+    subscription.resume();
+    expect(controller.isPaused, isFalse);
+    expect(await subscription.cancel(), 42);
+    expect(controller.hasListener, isFalse);
+  });
+
+  group("cancelOnError behavior", () {
+    for (var original in [false, true]) {
+      group("source/new subscription: ${original ? "yes" : "no"}", () {
+        test("no", () async {
+          var stream = createErrorStream();
+          var sourceSubscription = stream.listen(null, cancelOnError: original);
+          var subscriptionStream =
+              new SubscriptionStream(sourceSubscription,
+                                     isCancelOnError: original);
+          var done = new Completer();
+          var events = [];
+          var subscription = subscriptionStream.listen(events.add,
+                                                       onError: events.add,
+                                                       onDone: done.complete);
+          await done.future;
+          var expected = [1, 2, "To err is divine!"];
+          // If neither subscription is cancelOnError, the fourth event
+          // goes through.
+          if (!original) expected.add(4);
+          expect(events, expected);
+        });
+
+        test("yes", () async {
+          var stream = createErrorStream();
+          var sourceSubscription = stream.listen(null, cancelOnError: original);
+          var subscriptionStream =
+              new SubscriptionStream(sourceSubscription,
+                                     isCancelOnError: original);
+          var completer = new Completer();
+          var events = [];
+          subscriptionStream.listen(events.add,
+                                    onError: (v) {
+                                      events.add(v);
+                                      completer.complete();
+                                    },
+                                    onDone: () => throw "should not happen",
+                                    cancelOnError: true);
+          await completer.future;
+          await flushMicrotasks();
+          expect(events, [1, 2, "To err is divine!"]);
+        });
+      });
+
+      for (var cancelOnError in [false, true]) {
+        group(cancelOnError ? "yes" : "no", () {
+          test("- no error, value goes to asFuture", () async {
+            var stream = createStream();
+            var sourceSubscription =
+                stream.listen(null, cancelOnError: original);
+            var subscriptionStream =
+                new SubscriptionStream(sourceSubscription,
+                                       isCancelOnError: original);
+            var subscription =
+                subscriptionStream.listen(null, cancelOnError: cancelOnError);
+            expect(subscription.asFuture(42), completion(42));
+          });
+
+          test("- error goes to asFuture", () async {
+            var stream = createErrorStream();
+            var sourceSubscription = stream.listen(null,
+                                                   cancelOnError: original);
+            var subscriptionStream =
+                new SubscriptionStream(sourceSubscription,
+                                       isCancelOnError: original);
+            var subscription =
+                subscriptionStream.listen(null, cancelOnError: cancelOnError);
+            expect(subscription.asFuture(), throws);
+          });
+        });
+      }
+    }
+
+    test("mislabeled cancelOnError:false source", () async {
+      var controller = new StreamController();
+      var sourceSubscription =
+          controller.stream.listen(null, cancelOnError: false);
+      var subscriptionStream =
+          new SubscriptionStream(sourceSubscription,
+                                 isCancelOnError: true);
+      var lastEvent;
+      var subscription = subscriptionStream.listen(
+          (v) { lastEvent = v; },
+          onError: (v) { lastEvent = v; },
+          onDone: () { throw "unreachable"; },
+          cancelOnError: true);
+      controller.add(1);
+      await flushMicrotasks();
+      expect(lastEvent, 1);
+      controller.addError(2);
+      await flushMicrotasks();
+      expect(lastEvent, 2);
+      expect(controller.hasListener, true);  // Not canceled!
+      controller.addError(3);
+      await flushMicrotasks();
+      // This is the badness you get when passing `true` incorrectly!
+      expect(lastEvent, 3);
+    });
+
+    test("mislabeled cancelOnError:true source", () async {
+      var controller = new StreamController();
+      var sourceSubscription =
+          controller.stream.listen(null, cancelOnError: true);
+      var subscriptionStream =
+          new SubscriptionStream(sourceSubscription,
+                                 isCancelOnError: false);
+      var lastEvent;
+      var subscription = subscriptionStream.listen(
+          (v) { lastEvent = v; },
+          onError: (v) { lastEvent = v; },
+          onDone: () { throw "unreachable"; },
+          cancelOnError: false);
+      controller.add(1);
+      await flushMicrotasks();
+      expect(lastEvent, 1);
+      controller.addError(2);
+      await flushMicrotasks();
+      expect(lastEvent, 2);
+      expect(controller.hasListener, false);  // Canceled!
+      // This is slightly wrong, but safe.
+    });
+  });
+}
+
+Future flushMicrotasks() => new Future.delayed(Duration.ZERO);
+
+Stream<int> createStream() async* {
+  yield 1;
+  await flushMicrotasks();
+  yield 2;
+  await flushMicrotasks();
+  yield 3;
+  await flushMicrotasks();
+  yield 4;
+}
+
+Stream<int> createErrorStream() {
+  StreamController controller = new StreamController<int>();
+  () async {
+    controller.add(1);
+    await flushMicrotasks();
+    controller.add(2);
+    await flushMicrotasks();
+    controller.addError("To err is divine!");
+    await flushMicrotasks();
+    controller.add(4);
+    await flushMicrotasks();
+    controller.close();
+  }();
+  return controller.stream;
+}
+
+Stream<int> createLongStream() async* {
+  for (int i = 0; i < 200; i++) yield i;
+}