Start switching hijacking to use StreamChannel.

test/hijack_test.dart

 // Copyright (c) 2014, 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:test/test.dart';
 import 'package:shelf/shelf.dart';
 
 import 'test_util.dart';
 
 void main() {
   test('hijacking a non-hijackable request throws a StateError', () {
-    expect(() => new Request('GET', LOCALHOST_URI).hijack((_, __) => null),
+    expect(() => new Request('GET', LOCALHOST_URI).hijack((_) => null),
         throwsStateError);
   });
 
   test('hijacking a hijackable request throws a HijackException and calls '
       'onHijack', () {
     var request = new Request('GET', LOCALHOST_URI,
         onHijack: expectAsync((callback) {
       var streamController = new StreamController();
       streamController.add([1, 2, 3]);
       streamController.close();
 
       var sinkController = new StreamController();
       expect(sinkController.stream.first, completion(equals([4, 5, 6])));
 
       callback(streamController.stream, sinkController);
     }));
 
-    expect(() => request.hijack(expectAsync((stream, sink) {
-      expect(stream.first, completion(equals([1, 2, 3])));
-      sink.add([4, 5, 6]);
-      sink.close();
+    expect(() => request.hijack(expectAsync((channel) {
+      expect(channel.stream.first, completion(equals([1, 2, 3])));
+      channel.sink.add([4, 5, 6]);
+      channel.sink.close();
     })), throwsA(new isInstanceOf<HijackException>()));
   });
 
   test('hijacking a hijackable request twice throws a StateError', () {
     // Assert that the [onHijack] callback is only called once.
     var request = new Request('GET', LOCALHOST_URI,
         onHijack: expectAsync((_) => null, count: 1));
 
-    expect(() => request.hijack((_, __) => null),
+    expect(() => request.hijack((_) => null),
         throwsA(new isInstanceOf<HijackException>()));
 
-    expect(() => request.hijack((_, __) => null), throwsStateError);
+    expect(() => request.hijack((_) => null), throwsStateError);
   });
 
   group('calling change', () {
     test('hijacking a non-hijackable request throws a StateError', () {
       var request = new Request('GET', LOCALHOST_URI);
       var newRequest = request.change();
-      expect(() => newRequest.hijack((_, __) => null), throwsStateError);
+      expect(() => newRequest.hijack((_) => null), throwsStateError);
     });
 
     test('hijacking a hijackable request throws a HijackException and calls '
         'onHijack', () {
       var request = new Request('GET', LOCALHOST_URI,
           onHijack: expectAsync((callback) {
         var streamController = new StreamController();
         streamController.add([1, 2, 3]);
         streamController.close();
 
         var sinkController = new StreamController();
         expect(sinkController.stream.first, completion(equals([4, 5, 6])));
 
         callback(streamController.stream, sinkController);
       }));
 
       var newRequest = request.change();
 
-      expect(() => newRequest.hijack(expectAsync((stream, sink) {
-        expect(stream.first, completion(equals([1, 2, 3])));
-        sink.add([4, 5, 6]);
-        sink.close();
+      expect(() => newRequest.hijack(expectAsync((channel) {
+        expect(channel.stream.first, completion(equals([1, 2, 3])));
+        channel.sink.add([4, 5, 6]);
+        channel.sink.close();
       })), throwsA(new isInstanceOf<HijackException>()));
     });
 
     test('hijacking the original request after calling change throws a '
         'StateError', () {
       // Assert that the [onHijack] callback is only called once.
       var request = new Request('GET', LOCALHOST_URI,
           onHijack: expectAsync((_) => null, count: 1));
 
       var newRequest = request.change();
 
-      expect(() => newRequest.hijack((_, __) => null),
+      expect(() => newRequest.hijack((_) => null),
           throwsA(new isInstanceOf<HijackException>()));
 
-      expect(() => request.hijack((_, __) => null), throwsStateError);
+      expect(() => request.hijack((_) => null), throwsStateError);
     });
   });
 }