Use a bare git repository for the repo cache.

utils/tests/pub/test_pub.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.
 
 /**
  * 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.
  */
@@ skipping 274 matching lines @@
  * This directory is of the form found in the global package cache.
  */
 DirectoryDescriptor packageCacheDir(String name, String version) {
   return dir("$name-$version", [
     file("$name.dart", 'main() => print("$name $version");')
   ]);
 }
 
 /**
  * Describes a directory for a Git package. This directory is of the form found
- * in the global package cache.
+ * in the revision cache of the global package cache.
  */
-DirectoryDescriptor gitPackageCacheDir(String name, [int modifier]) {
+DirectoryDescriptor gitPackageRevisionCacheDir(String name, [int modifier]) {
   var value = name;
   if (modifier != null) value = "$name $modifier";
   return dir(new RegExp("$name${@'-[a-f0-9]+'}"), [
     file('$name.dart', 'main() => "$value";')
   ]);
 }
 
 /**
+ * Describes a directory for a Git package. This directory is of the form found
+ * in the repo cache of the global package cache.
+ */
+DirectoryDescriptor gitPackageRepoCacheDir(String name) {
+  return dir(new RegExp("$name${@'-[a-f0-9]+'}"), [
+    dir('branches'),
+    dir('hooks'),
+    dir('info'),
+    dir('objects'),
+    dir('refs')
+  ]);
+}
+
+/**
  * Describes the `packages/` directory containing all the given [packages],
  * which should be name/version pairs. The packages will be validated against
  * the format produced by the mock package server.
  *
  * A package with a null version should not be installed.
  */
 DirectoryDescriptor packagesDir(Map<String, String> packages) {
   var contents = <Descriptor>[];
   packages.forEach((name, version) {
     if (version == null) {
@@ skipping 492 matching lines @@
  * Describes a directory and its contents. These are used both for setting up
  * an expected directory tree before running a test, and for validating that
  * the file system matches some expectations after running it.
  */
 class DirectoryDescriptor extends Descriptor {
   /**
    * The files and directories contained in this directory.
    */
   final List<Descriptor> contents;
 
-  DirectoryDescriptor(Pattern name, this.contents) : super(name);
+  DirectoryDescriptor(Pattern name, List<Descriptor> contents)
+    : this.contents = contents == null ? <Descriptor>[] : contents,
+      super(name);
 
   /**
    * Creates the file within [dir]. Returns a [Future] that is completed after
    * the creation is done.
    */
   Future<Directory> create(parentDir) {
     // Create the directory.
     return ensureDir(join(parentDir, _stringName)).chain((dir) {
       if (contents == null) return new Future<Directory>.immediate(dir);
 
@@ skipping 122 matching lines @@
       return superCreate(parentDir).chain((rootDir) {
         return _runGit(['rev-parse', ref], rootDir);
       }).transform((output) {
         completer.complete(output[0]);
         return null;
       });
     });
     return completer.future;
   }
 
+  /// Schedule a Git command to run in this repository.
+  void scheduleGit(List<String> args) {
+    _schedule((parentDir) {
+      var gitDir = new Directory(join(parentDir, name));
+      return _runGit(args, gitDir);
+    });
+  }
+
   Future<String> _runGit(List<String> args, Directory workingDir) {
     return runProcess('git', args, workingDir: workingDir.path).
       transform((result) {
         if (!result.success) throw "Error running git: ${result.stderr}";
         return result.stdout;
       });
   }
 }
 
 /**
@@ skipping 120 matching lines @@
 }
 
 /**
  * Schedules a callback to be called after Pub is run with [runPub], even if it
  * fails.
  */
 void _scheduleCleanup(_ScheduledEvent event) {
   if (_scheduledCleanup == null) _scheduledCleanup = [];
   _scheduledCleanup.add(event);
 }