Refactor Source and SourceRegistry.

test/lock_file_test.dart

Index: test/lock_file_test.dart
diff --git a/test/lock_file_test.dart b/test/lock_file_test.dart
index 35a1e0b17151e8af91f37ae08752c36bc922cc11..c59202e4424ac9b77aa699a0fb4ed30749e65123 100644
--- a/test/lock_file_test.dart
+++ b/test/lock_file_test.dart
@@ -2,13 +2,11 @@
 // 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.
 
-import 'dart:async';
-
 import 'package:pub/src/lock_file.dart';
 import 'package:pub/src/package.dart';
-import 'package:pub/src/pubspec.dart';
 import 'package:pub/src/source.dart';
 import 'package:pub/src/source_registry.dart';
+import 'package:pub/src/system_cache.dart';
 import 'package:pub_semver/pub_semver.dart';
 import 'package:test/test.dart';
 import 'package:yaml/yaml.dart';
@@ -16,17 +14,8 @@ import 'package:yaml/yaml.dart';
 class MockSource extends Source {
   final String name = 'mock';
 
-  Future<List<PackageId>> doGetVersions(PackageRef ref) =>
-      throw new UnsupportedError("Cannot get mock package versions.");
-
-  Future<Pubspec> doDescribe(PackageId id) => throw new UnsupportedError(
-      "Cannot describe mock packages.");
-
-  Future get(PackageId id, String symlink) => throw new UnsupportedError(
-      "Cannot get a mock package.");
-
-  String getDirectory(PackageId id) => throw new UnsupportedError(
-      "Cannot get the directory for mock packages.");
+  BoundSource bind(SystemCache cache) =>
+      throw new UnsupportedError("Cannot download mock packages.");
 
   PackageRef parseRef(String name, description, {String containingPath}) {
     if (!description.endsWith(' desc')) throw new FormatException('Bad');