Use "pub list-package-dirs" to resolve package URIs in analysis server.

pkg/analysis_server/test/mocks.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.
 
 library mocks;
 
 import 'dart:async';
 import 'dart:io';
 
 @MirrorsUsed(targets: 'mocks', override: '*')
 import 'dart:mirrors';
 
+import 'package:analysis_server/src/analysis_server.dart';
+import 'package:analysis_server/src/channel.dart';
+import 'package:analysis_server/src/operation/operation_analysis.dart';
+import 'package:analysis_server/src/operation/operation.dart';
+import 'package:analysis_server/src/package_map_provider.dart';
+import 'package:analysis_server/src/protocol.dart';
+import 'package:analysis_server/src/resource.dart' as resource;
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
-import 'package:analysis_server/src/analysis_server.dart';
-import 'package:analysis_server/src/channel.dart';
-import 'package:analysis_server/src/protocol.dart';
-import 'package:analysis_server/src/resource.dart' as resource;
 import 'package:matcher/matcher.dart';
 import 'package:mock/mock.dart';
 import 'package:unittest/unittest.dart';
-import 'package:analysis_server/src/operation/operation_analysis.dart';
-import 'package:analysis_server/src/operation/operation.dart';
 
 /**
  * Answer the absolute path the the SDK relative to the currently running
  * script or throw an exception if it cannot be found.
  */
 String get sdkPath {
   Uri sdkUri = Platform.script.resolve('../../../sdk/');
 
   // Verify the directory exists
   Directory sdkDir = new Directory.fromUri(sdkUri);
@@ skipping 368 matching lines @@
 
   // Not used.
   @override
   String get sdkVersion => throw unimplemented;
 
   // Not used.
   @override
   List<String> get uris => throw unimplemented;
 }
 
+/**
+ * A mock [PackageMapProvider].
+ */
+class MockPackageMapProvider implements PackageMapProvider {
+  Map<String, resource.Folder> packageMap = <String, resource.Folder>{};
+
+  @override
+  Map<String, resource.Folder> computePackageMap(resource.Folder folder) {
+    return packageMap;
+  }
+}