Take Sam Elkhateeb's path for "path" dependencies and clean it up some.

utils/tests/pub/install/path/path_is_file_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 when path is a file', () {
+    dir('foo', [
+      libDir('foo'),
+      libPubspec('foo', '0.0.1')
+    ]).scheduleCreate();
+
+    file('dummy.txt', '').scheduleCreate();
+    var dummyPath = path.join(sandboxDir, 'dummy.txt');
+
+    dir(appPath, [
+      pubspec({
+        "name": "myapp",
+        "dependencies": {
+          "foo": {"path": dummyPath}
+        }
+      })
+    ]).scheduleCreate();
+
+    schedulePub(args: ['install'],
+        error: new RegExp("Path dependency for package 'foo' must refer to a "
+                          "directory, not a file. Was '$dummyPath'."),
+        exitCode: exit_codes.DATA);
+  });
+}