Fix transformer tests.

test/stream_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:convert';
 
 import 'package:async/async.dart';
 import 'package:stream_channel/stream_channel.dart';
 import 'package:test/test.dart';
@@ skipping 23 matching lines @@
     streamController.close();
     expect(otherSinkController.stream.toList(), completion(equals([1, 2, 3])));
 
     otherStreamController.add(4);
     otherStreamController.add(5);
     otherStreamController.add(6);
     otherStreamController.close();
     expect(sinkController.stream.toList(), completion(equals([4, 5, 6])));
   });
 
-  test("transform() transforms the channel", () {
+  test("transform() transforms the channel", () async {
     var transformed = channel.transform(
         new StreamChannelTransformer.fromCodec(UTF8));
 
     streamController.add([102, 111, 111, 98, 97, 114]);
     streamController.close();
-    expect(transformed.stream.toList(), completion(equals(["foobar"])));
+    expect(await transformed.stream.toList(), equals(["foobar"]));
 
     transformed.sink.add("fblthp");
     transformed.sink.close();
     expect(sinkController.stream.toList(),
         completion(equals([[102, 98, 108, 116, 104, 112]])));
   });
 
-  test("transformStream() transforms only the stream", () {
+  test("transformStream() transforms only the stream", () async {
     var transformed = channel.transformStream(UTF8.decoder);
 
     streamController.add([102, 111, 111, 98, 97, 114]);
     streamController.close();
-    expect(transformed.stream.toList(), completion(equals(["foobar"])));
+    expect(await transformed.stream.toList(), equals(["foobar"]));
 
     transformed.sink.add("fblthp");
     transformed.sink.close();
     expect(sinkController.stream.toList(),
         completion(equals(["fblthp"])));
   });
 
-  test("transformSink() transforms only the sink", () {
+  test("transformSink() transforms only the sink", () async {
     var transformed = channel.transformSink(
         new StreamSinkTransformer.fromStreamTransformer(UTF8.encoder));
 
     streamController.add([102, 111, 111, 98, 97, 114]);
     streamController.close();
-    expect(transformed.stream.toList(),
-        completion(equals([[102, 111, 111, 98, 97, 114]])));
+    expect(await transformed.stream.toList(),
+        equals([[102, 111, 111, 98, 97, 114]]));
 
     transformed.sink.add("fblthp");
     transformed.sink.close();
     expect(sinkController.stream.toList(),
         completion(equals([[102, 98, 108, 116, 104, 112]])));
   });
 
   test("changeStream() changes the stream", () {
     var newController = new StreamController();
     var changed = channel.changeStream((stream) {
@@ skipping 17 matching lines @@
       return newController.sink;
     });
 
     expect(newController.stream.toList(), completion(equals([10])));
     streamController.stream.listen(expectAsync((_) {}, count: 0));
 
     changed.sink.add(10);
     changed.sink.close();
   });
 }