Use shelf handlers in ScheduledServer.

sdk/lib/_internal/pub/test/hosted/version_negotiation_test.dart

 // Copyright (c) 2012, 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.
 
 library pub_tests;
 
 import 'package:scheduled_test/scheduled_server.dart';
 import 'package:scheduled_test/scheduled_test.dart';
+import 'package:shelf/shelf.dart' as shelf;
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 main() {
   initConfig();
 
   forBothPubGetAndUpgrade((command) {
     integration('sends the correct Accept header', () {
       var server = new ScheduledServer();
 
       d.appDir({
         "foo": {
           "hosted": {
             "name": "foo",
             "url": server.url.then((url) => url.toString())
           }
         }
       }).create();
 
       var pub = startPub(args: [command.name]);
 
       server.handle('GET', '/api/packages/foo', (request) {
-        expect(request.headers['Accept'], ['application/vnd.pub.v2+json']);
+        expect(request.headers['accept'],
+            equals('application/vnd.pub.v2+json'));
+        return new shelf.Response(200);
       });
 
       pub.kill();
     });
 
     integration('prints a friendly error if the version is out-of-date', () {
       var server = new ScheduledServer();
 
       d.appDir({
         "foo": {
           "hosted": {
             "name": "foo",
             "url": server.url.then((url) => url.toString())
           }
         }
       }).create();
 
       var pub = startPub(args: [command.name]);
 
-      server.handle('GET', '/api/packages/foo', (request) {
-        request.response.statusCode = 406;
-        request.response.close();
-      });
+      server.handle('GET', '/api/packages/foo',
+          (request) => new shelf.Response(406));
 
       // TODO(nweiz): this shouldn't request the versions twice (issue 11077).
-      server.handle('GET', '/api/packages/foo', (request) {
-        request.response.statusCode = 406;
-        request.response.close();
-      });
+      server.handle('GET', '/api/packages/foo',
+          (request) => new shelf.Response(406));
 
       pub.shouldExit(1);
 
       pub.stderr.expect(emitsLines(
           "Pub 0.1.2+3 is incompatible with the current version of 127.0.0.1.\n"
           "Upgrade pub to the latest version and try again."));
     });
   });
 }