Move pubspec caching into each source.

test/version_solver_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 pub_upgrade_test;
 
 import 'dart:async';
 
 import 'package:pub/src/lock_file.dart';
 import 'package:pub/src/log.dart' as log;
@@ skipping 1377 matching lines @@
   MockSource(this.name);
 
   dynamic parseDescription(String containingPath, description,
                              {bool fromLockFile: false}) => description;
 
   bool descriptionsEqual(description1, description2) =>
       description1 == description2;
 
   String getDirectory(PackageId id) => '${id.name}-${id.version}';
 
-  Future<List<Pubspec>> getVersions(String name, String description) {
-    return new Future.sync(() {
-      // Make sure the solver doesn't request the same thing twice.
-      if (_requestedVersions.contains(description)) {
-        throw new Exception('Version list for $description was already '
-            'requested.');
-      }
+  Future<List<PackageId>> doGetVersions(PackageRef ref) async {
+    // Make sure the solver doesn't request the same thing twice.
+    if (_requestedVersions.contains(ref.description)) {
+      throw new Exception('Version list for $description was already '
+          'requested.');
+    }
 
-      _requestedVersions.add(description);
+    _requestedVersions.add(ref.description);
 
-      if (!_packages.containsKey(description)){
-        throw new Exception('MockSource does not have a package matching '
-            '"$description".');
-      }
+    if (!_packages.containsKey(ref.description)){
+      throw new Exception('MockSource does not have a package matching '
+          '"${ref.description}".');
+    }
 
-      return _packages[description].values
-          .map((package) => package.pubspec).toList();
-    });
+    return _packages[ref.description].values
+        .map((package) => ref.atVersion(package.version)).toList();
   }
 
   Future<Pubspec> describeUncached(PackageId id) {
     return new Future.sync(() {
       // Make sure the solver doesn't request the same thing twice.
       if (_requestedPubspecs.containsKey(id.description) &&
           _requestedPubspecs[id.description].contains(id.version)) {
         throw new Exception('Pubspec for $id was already requested.');
       }
 
@@ skipping 105 matching lines @@
   }
 
   var source = "mock1";
   if (match[7] != null) {
     source = match[7];
     if (source == "root") source = null;
   }
 
   return new PackageId(name, source, parsedVersion, description);
 }