pub: don't start the admin server if no --admin-port flag was given.

sdk/lib/_internal/pub/test/serve/utils.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS d.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 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 137 matching lines @@
 /// Unlike [pubServe], this doesn't determine the port number of the server, and
 /// so may be used to test for errors in the initialization process.
 ///
 /// Returns the `pub serve` process.
 ScheduledProcess startPubServe({Iterable<String> args,
     bool createWebDir: true}) {
   var pubArgs = [
     "serve",
     "--port=0", // Use port 0 to get an ephemeral port.
     "--force-poll",
+    "--admin-port=0", // Use port 0 to get an ephemeral port.
     "--log-admin-url"
   ];
 
   if (args != null) pubArgs.addAll(args);
 
   // Dart2js can take a long time to compile dart code, so we increase the
   // timeout to cope with that.
   currentSchedule.timeout *= 1.5;
 
   if (createWebDir) d.dir(appPath, [d.dir("web")]).create();
@@ skipping 48 matching lines @@
   return _pubServer;
 }
 
 /// The regular expression for parsing pub's output line describing the URL for
 /// the server.
 final _parsePortRegExp = new RegExp(r"([^ ]+) +on http://localhost:(\d+)");
 
 /// Parses the port number from the "Running admin server on localhost:1234"
 /// line printed by pub serve.
 bool _parseAdminPort(String line) {
+  expect(line, startsWith('Running admin server on'));
   var match = _parsePortRegExp.firstMatch(line);
   if (match == null) return false;
   _adminPort = int.parse(match[2]);
   return true;
 }
 
 /// Parses the port number from the "Serving blah on localhost:1234" line
 /// printed by pub serve.
 bool _parsePort(String line) {
   var match = _parsePortRegExp.firstMatch(line);
@@ skipping 255 matching lines @@
 /// included. Unlike [getServerUrl], this should only be called after the ports
 /// are known.
 String _getServerUrlSync([String root, String path]) {
   if (root == null) root = 'web';
   expect(_ports, contains(root));
   var url = "http://localhost:${_ports[root]}";
   if (path != null) url = "$url/$path";
   return url;
 }