Clean up the semantics of package descriptions.

test/pubspec_test.dart

 // Copyright (c) 2012, 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 pubspec_test;
 
 import 'dart:async';
 
 import 'package:pub/src/package.dart';
 import 'package:pub/src/pubspec.dart';
 import 'package:pub/src/source.dart';
 import 'package:pub/src/source/path.dart';
 import 'package:pub/src/source_registry.dart';
 import 'package:pub_semver/pub_semver.dart';
 import 'package:test/test.dart';
 
 import 'test_pub.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.");
 
-  dynamic parseDescription(String filePath, description,
-                           {bool fromLockFile: false}) {
+  PackageRef parseRef(String name, description, {String containingPath}) {
     if (description != 'ok') throw new FormatException('Bad');
-    return description;
+    return new PackageRef(name, this.name, description);
   }
 
+  PackageId parseId(String name, Version version, description) =>
+      new PackageId(name, this.name, version, description);
+
   bool descriptionsEqual(description1, description2) =>
       description1 == description2;
 
   String packageName(description) => 'foo';
 }
 
 main() {
   group('parse()', () {
     var sources = new SourceRegistry();
     sources.register(new MockSource());
@@ skipping 483 matching lines @@
       test("uses the key if the value is null", () {
         var pubspec = new Pubspec.parse('''
 executables:
   command:
 ''', sources);
         expect(pubspec.executables['command'], equals('command'));
       });
     });
   });
 }