Use the cached pubspec if possible for describing hosted packages.

utils/tests/pub/test_pub.dart

 // Copyright (c) 2013, 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.
 
 /// Test infrastructure for testing pub. Unlike typical unit tests, most pub
 /// tests are integration tests that stage some stuff on the file system, run
 /// pub, and then validate the results. This library provides an API to build
 /// tests like that.
 library test_pub;
 
@@ skipping 39 matching lines @@
   }
 }
 
 /// Returns whether we're running on a Dart build bot.
 bool get runningOnBuildbot =>
   Platform.environment.containsKey('BUILDBOT_BUILDERNAME');
 
 /// The current [HttpServer] created using [serve].
 var _server;
 
+/// The list of paths that have been requested from the server since the last
+/// call to [getRequestedPaths].
+final _requestedPaths = <String>[];
+
 /// The cached value for [_portCompleter].
 Completer<int> _portCompleterCache;
 
 /// The completer for [port].
 Completer<int> get _portCompleter {
   if (_portCompleterCache != null) return _portCompleterCache;
   _portCompleterCache = new Completer<int>();
   currentSchedule.onComplete.schedule(() {
     _portCompleterCache = null;
   }, 'clearing the port completer');
   return _portCompleterCache;
 }
 
 /// A future that will complete to the port used for the current server.
 Future<int> get port => _portCompleter.future;
 
+/// Gets the list of paths that have been requested from the server since the
+/// last time this was called (or since the server was first spun up).
+Future<List<String>> getRequestedPaths() {
+  return schedule(() {
+    var paths = _requestedPaths.toList();
+    _requestedPaths.clear();
+    return paths;
+  });
+}
+
 /// Creates an HTTP server to serve [contents] as static files. This server will
 /// exist only for the duration of the pub run.
 ///
 /// Subsequent calls to [serve] will replace the previous server.
 void serve([List<d.Descriptor> contents]) {
   var baseDir = d.dir("serve-dir", contents);
 
   schedule(() {
     return _closeServer().then((_) {
       return SafeHttpServer.bind("127.0.0.1", 0).then((server) {
         _server = server;
         server.listen((request) {
           var response = request.response;
           try {
             var path = request.uri.path.replaceFirst("/", "");
+
+            if (_requestedPaths == null) _requestedPaths = <String>[];
+            _requestedPaths.add(path);
+
             response.persistentConnection = false;
             var stream = baseDir.load(path);
 
             new ByteStream(stream).toBytes().then((data) {
               response.statusCode = 200;
               response.contentLength = data.length;
               response.add(data);
               response.close();
             }).catchError((e) {
               response.statusCode = 404;
@@ skipping 509 matching lines @@
   bool matches(item, MatchState matchState) {
     if (item is! Pair) return false;
     return _firstMatcher.matches(item.first, matchState) &&
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }