Support relative paths in path dependencies.

utils/tests/pub/install/path/relative_symlink_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 dependency with absolute path', () {
-    dir('foo', [
-      libDir('foo'),
-      libPubspec('foo', '0.0.1')
+  integration("generates a symlink with a relative path", () {
+    dir("foo", [
+      libDir("foo"),
+      libPubspec("foo", "0.0.1")
     ]).scheduleCreate();
 
     dir(appPath, [
       pubspec({
         "name": "myapp",
         "dependencies": {
-          "foo": {"path": path.join(sandboxDir, "foo")}
+          "foo": {"path": "../foo"}
         }
       })
     ]).scheduleCreate();
 
     schedulePub(args: ["install"],
         output: new RegExp(r"Dependencies installed!$"));
 
-    dir(packagesPath, [
-      dir("foo", [
-        file("foo.dart", 'main() => "foo";')
-      ])
-    ]).scheduleValidate();
+    dir("moved").scheduleCreate();
 
-    // Move the packages directory and ensure the symlink still works. That
-    // will validate that we actually created an absolute symlink.
-    dir("moved").scheduleCreate();
-    scheduleRename(packagesPath, "moved/packages");
+    // Move the app and package. Since they are still next to each other, it
+    // should still be found.
+    scheduleRename("foo", path.join("moved", "foo"));
+    scheduleRename(appPath, path.join("moved", appPath));
 
-    dir("moved/packages", [
-      dir("foo", [
-        file("foo.dart", 'main() => "foo";')
+    dir("moved", [
+      dir(packagesPath, [
+        dir("foo", [
+          file("foo.dart", 'main() => "foo";')
+        ])
       ])
     ]).scheduleValidate();
   });
 }