Revert "Return futures on Stream.cancel when possible."

tests/lib/async/stream_subscription_cancel_test.dart

 // Copyright (c) 2013, 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.
 
 // Test the StreamSubscription.cancel return Future.
 library stream_subscription_cancel;
 
 import 'dart:async';
 import 'package:unittest/unittest.dart';
 
 void main() {
   test('subscription.cancel', () {
     var completer = new Completer();
     StreamController controller = new StreamController(
         onCancel: () => completer.future);
 
     bool done = false;
     expect(controller.stream.listen(null).cancel().then((_) => done),
            completion(equals(true)));
 
     Timer.run(() {
       done = true;
       completer.complete();
     });
   });
 
   test('subscription.cancel after close', () {
     var completer = new Completer();
     StreamController controller = new StreamController(
-        onCancel: () {
-          completer.complete();
-          return completer.future;
-        });
+        onCancel: completer.complete);
 
     controller.close();
 
-    var completer2 = new Completer();
     var sub;
     void onDone() {
-      sub.cancel().then(completer2.complete);
+      expect(sub.cancel(), isNull);
     }
 
     sub = controller.stream.listen(null, onDone: onDone);
     expect(completer.future, completes);
-    expect(completer2.future, completes);
   });
 
   test('subscription.cancel after error', () {
     var completer = new Completer();
     StreamController controller = new StreamController(
         onCancel: () => completer.future);
 
     controller.addError("error");
 
     bool done = false;
@@ skipping 77 matching lines @@
     controller.close();
 
     void onDone() {
       fail("onDone is unexpected");
     }
     controller.stream
       .listen(null, onDone: onDone)
       .cancel();
     expect(doneCompleter.future, completion(equals(true)));
   });
-
-  test('subscription.cancel through map', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.map((x) => x).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through asyncMap', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.asyncMap((x) => x).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through asyncExpand', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.asyncExpand((x) => x).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through handleError', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.handleError((x) => x).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through skip', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.skip(1).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through take', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.take(1).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through skipWhile', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.skipWhile((x) => true).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through takeWhile', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.takeWhile((x) => true).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through timeOut', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var duration = const Duration(hours: 5);
-    var future = controller.stream.timeout(duration).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through transform', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var transformer =
-        new StreamTransformer.fromHandlers(handleData: (x, y) {});
-    var future = controller.stream.transform(transformer).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
-
-  test('subscription.cancel through where', () {
-    var completer = new Completer();
-    StreamController controller = new StreamController(
-        onCancel: () => completer.future);
-
-    bool done = false;
-    var future = controller.stream.where((x) => true).listen(null).cancel();
-
-    expect(future.then((_) => done = true), completion(equals(true)));
-
-    Timer.run(() {
-      expect(done, isFalse);
-      completer.complete();
-    });
-  });
 }