Support relative paths in path dependencies.

utils/tests/pub/install/path/relative_path_test.dart

 // Copyright (c) 2013, 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.
 
+import '../../../../../pkg/path/lib/path.dart' as path;
+
 import '../../../../pub/exit_codes.dart' as exit_codes;
 import '../../test_pub.dart';
 
 main() {
   initConfig();
-  integration('path dependencies cannot use relative paths', () {
+  integration("can use relative path", () {
+    dir("foo", [
+      libDir("foo"),
+      libPubspec("foo", "0.0.1")
+    ]).scheduleCreate();
+
     dir(appPath, [
       pubspec({
         "name": "myapp",
         "dependencies": {
           "foo": {"path": "../foo"}
         }
       })
     ]).scheduleCreate();
 
-    schedulePub(args: ['install'],
-        error: new RegExp("Path dependency for package 'foo' must be an "
-                          "absolute path. Was '../foo'."),
-        exitCode: exit_codes.DATA);
+    schedulePub(args: ["install"],
+        output: new RegExp(r"Dependencies installed!$"));
+
+    dir(packagesPath, [
+      dir("foo", [
+        file("foo.dart", 'main() => "foo";')
+      ])
+    ]).scheduleValidate();
   });
-}
+
+  integration("path is relative to containing pubspec", () {
+    dir("relative", [
+      dir("foo", [
+        libDir("foo"),
+        libPubspec("foo", "0.0.1", deps: [
+          {"path": "../bar"}
+        ])
+      ]),
+      dir("bar", [
+        libDir("bar"),
+        libPubspec("bar", "0.0.1")
+      ])
+    ]).scheduleCreate();
+
+    dir(appPath, [
+      pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "foo": {"path": "../relative/foo"}
+        }
+      })
+    ]).scheduleCreate();
+
+    schedulePub(args: ["install"],
+        output: new RegExp(r"Dependencies installed!$"));
+
+    dir(packagesPath, [
+      dir("foo", [
+        file("foo.dart", 'main() => "foo";')
+      ]),
+      dir("bar", [
+        file("bar.dart", 'main() => "bar";')
+      ])
+    ]).scheduleValidate();
+  });
+}