support path activations

diff --git a/lib/pub_cache.dart b/lib/pub_cache.dart
index a2c8b00..3f980e5 100644
--- a/lib/pub_cache.dart
+++ b/lib/pub_cache.dart

@@ -185,6 +185,8 @@
           }
           return null;
         });
+      } else if (source == 'path') {
+        return new PackageRefImpl.path(key, m['version'], m['description']);
       } else {
         return new PackageRefImpl(source, key, m['version']);
       }

diff --git a/lib/src/impl.dart b/lib/src/impl.dart
index fe6dfcb..a2b3e7f 100644
--- a/lib/src/impl.dart
+++ b/lib/src/impl.dart

@@ -29,6 +29,10 @@
     return new GitPackageRefImpl(name, ver, description, resolver);
   }
 
+  factory PackageRefImpl.path(String name, String ver, Map description) {
+    return new PathPackageRefImpl(name, ver, description);
+  }
+
   Package resolve() => _resolver == null ? null : _resolver(this);
 }
 
@@ -47,6 +51,25 @@
   String get url => _description['url'];
 }
 
+class PathPackageRefImpl extends PackageRefImpl {
+  final Map _description;
+
+  PathPackageRefImpl(String name, String ver, this._description) :
+      super('path', name, ver);
+
+  /// The path to the local package.
+  String get path => _description['path'];
+
+  bool get relative => _description['relative'] == true;
+
+  Package resolve() {
+    Directory dir = new Directory(path);
+    return dir.existsSync() ? new Package(dir, name, version) : null;
+  }
+}
+
+/// A reference to a package in the pub cache (for instance, something in
+/// `~/.pub-cache/hosted/pub.dartlang.org/`).
 class DirectoryPackageRef extends PackageRef {
   final String sourceType;
   final Directory directory;
@@ -70,6 +93,7 @@
   Package resolve() => new Package(directory, name, version);
 }
 
+/// A reference to a package in the pub cache; something in `~/.pub-cache/git/`.
 class GitDirectoryPackageRef extends PackageRef {
   final String sourceType;
   final Directory directory;

diff --git a/tool/travis.sh b/tool/travis.sh
index 8914355..dc1d87b 100755
--- a/tool/travis.sh
+++ b/tool/travis.sh

@@ -9,7 +9,8 @@
 
 # Activate some packages for use while running tests.
 pub global activate dart_coveralls
-pub global activate --source git https://github.com/dart-lang/pub_cache.git
+pub global activate --source git https://github.com/dart-lang/test.git
+pub global activate --source path .
 
 # Verify that the libraries are error free.
 dartanalyzer --fatal-warnings \