Add following tests :

runtime/observatory/tests/service/auth_token_test.dart

Index: runtime/observatory/tests/service/auth_token_test.dart
diff --git a/runtime/observatory/tests/service/auth_token_test.dart b/runtime/observatory/tests/service/auth_token_test.dart
index ce75e4f298b595e9a589d3ce7639093771d29205..6d38fcaa310dd89577af4ee17985b72134f304f0 100644
--- a/runtime/observatory/tests/service/auth_token_test.dart
+++ b/runtime/observatory/tests/service/auth_token_test.dart
@@ -1,10 +1,11 @@
-// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// 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.
 // VMOptions=--error_on_bad_type --error_on_bad_override
 
 import 'dart:async';
 import 'dart:developer';
+import 'dart:io' as io;
 import 'package:observatory/service_io.dart';
 import 'package:unittest/unittest.dart';
 import 'test_helper.dart';
@@ -19,6 +20,26 @@ Future<Null> testeeBefore() async {
   expect(info.serverUri.pathSegments.length, greaterThan(1));
   // Sanity check the length of the auth token.
   expect(info.serverUri.pathSegments[0].length, greaterThan(8));
+
+  // Try connecting to the server without the auth token, it should throw
+  // an exception.
+  var port = info.serverUri.port;
+  var url = Uri.parse('http://127.0.0.1:$port');
+  var httpClient = new io.HttpClient();
+  try {
+    var request = await httpClient.getUrl(url);
+    expect(true, false);
+  } catch (e) {
+    expect(true, true);
+  }
+
+  // Try connecting to the server with the auth token, it should succeed.
+  try {
+    var request = await httpClient.getUrl(info.serverUri);
+    expect(true, true);
+  } catch (e) {
+    expect(true, false);
+  }
 }
 
 var tests = [