Test empty strings arguments to path.join().

pkg/path/test/url_test.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.
 
 import 'package:unittest/unittest.dart';
 import 'package:path/path.dart' as path;
 
 main() {
   var builder = new path.Builder(style: path.Style.url,
       root: 'http://dartlang.org/root/path');
@@ skipping 205 matching lines @@
           'http://dartlang.org/b/c');
       expect(builder.join('file://', 'a', '/b', 'c'), 'file:///b/c');
       expect(builder.join('file://', 'a', '/b', 'c', '/d'), 'file:///d');
     });
 
     test('ignores trailing nulls', () {
       expect(builder.join('a', null), equals('a'));
       expect(builder.join('a', 'b', 'c', null, null), equals('a/b/c'));
     });
 
+    test('ignores empty strings', () {
+      expect(builder.join(''), '');
+      expect(builder.join('', ''), '');
+      expect(builder.join('', 'a'), 'a');
+      expect(builder.join('a', '', 'b', '', '', '', 'c'), 'a/b/c');
+      expect(builder.join('a', 'b', ''), 'a/b');
+    });
+
     test('disallows intermediate nulls', () {
       expect(() => builder.join('a', null, 'b'), throwsArgumentError);
       expect(() => builder.join(null, 'a'), throwsArgumentError);
     });
   });
 
   group('joinAll', () {
     test('allows more than eight parts', () {
       expect(builder.joinAll(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']),
           'a/b/c/d/e/f/g/h/i');
@@ skipping 408 matching lines @@
         Uri.parse('http://dartlang.org/path/to/foo'));
     expect(builder.toUri('http://dartlang.org/path/to/foo/'),
         Uri.parse('http://dartlang.org/path/to/foo/'));
     expect(builder.toUri('file:///path/to/foo'),
         Uri.parse('file:///path/to/foo'));
     expect(builder.toUri('foo/bar'), Uri.parse('foo/bar'));
     expect(builder.toUri('http://dartlang.org/path/to/foo%23bar'),
         Uri.parse('http://dartlang.org/path/to/foo%23bar'));
   });
 }