Refactor pkg/path.

pkg/path/test/windows_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.
 
 library path.test.windows_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:path/path.dart' as path;
 
 import 'utils.dart';
 
 main() {
-  var builder = new path.Builder(style: path.Style.windows,
-                                 root: r'C:\root\path');
-
-  if (new path.Builder().style == path.Style.windows) {
-    group('absolute', () {
-      expect(path.absolute(r'a\b.txt'), path.join(path.current, r'a\b.txt'));
-      expect(path.absolute(r'C:\a\b.txt'), r'C:\a\b.txt');
-      expect(path.absolute(r'\\a\b.txt'), r'\\a\b.txt');
-    });
-  }
+  var context = new path.Context(style: path.Style.windows,
+                                 current: r'C:\root\path');
 
   group('separator', () {
-    expect(builder.separator, '\\');
+    expect(context.separator, '\\');
   });
 
   test('extension', () {
-    expect(builder.extension(''), '');
-    expect(builder.extension('.'), '');
-    expect(builder.extension('..'), '');
-    expect(builder.extension('a/..'), '');
-    expect(builder.extension('foo.dart'), '.dart');
-    expect(builder.extension('foo.dart.js'), '.js');
-    expect(builder.extension('foo bar\gule fisk.dart.js'), '.js');
-    expect(builder.extension(r'a.b\c'), '');
-    expect(builder.extension('a.b/c.d'), '.d');
-    expect(builder.extension(r'~\.bashrc'), '');
-    expect(builder.extension(r'a.b/c'), r'');
-    expect(builder.extension(r'foo.dart\'), '.dart');
-    expect(builder.extension(r'foo.dart\\'), '.dart');
+    expect(context.extension(''), '');
+    expect(context.extension('.'), '');
+    expect(context.extension('..'), '');
+    expect(context.extension('a/..'), '');
+    expect(context.extension('foo.dart'), '.dart');
+    expect(context.extension('foo.dart.js'), '.js');
+    expect(context.extension('foo bar\gule fisk.dart.js'), '.js');
+    expect(context.extension(r'a.b\c'), '');
+    expect(context.extension('a.b/c.d'), '.d');
+    expect(context.extension(r'~\.bashrc'), '');
+    expect(context.extension(r'a.b/c'), r'');
+    expect(context.extension(r'foo.dart\'), '.dart');
+    expect(context.extension(r'foo.dart\\'), '.dart');
   });
 
   test('rootPrefix', () {
-    expect(builder.rootPrefix(''), '');
-    expect(builder.rootPrefix('a'), '');
-    expect(builder.rootPrefix(r'a\b'), '');
-    expect(builder.rootPrefix(r'C:\a\c'), r'C:\');
-    expect(builder.rootPrefix('C:\\'), r'C:\');
-    expect(builder.rootPrefix('C:/'), 'C:/');
-    expect(builder.rootPrefix(r'\\server\share\a\b'), r'\\server\share');
-    expect(builder.rootPrefix(r'\a\b'), r'\');
-    expect(builder.rootPrefix(r'/a/b'), r'/');
-    expect(builder.rootPrefix(r'\'), r'\');
-    expect(builder.rootPrefix(r'/'), r'/');
+    expect(context.rootPrefix(''), '');
+    expect(context.rootPrefix('a'), '');
+    expect(context.rootPrefix(r'a\b'), '');
+    expect(context.rootPrefix(r'C:\a\c'), r'C:\');
+    expect(context.rootPrefix('C:\\'), r'C:\');
+    expect(context.rootPrefix('C:/'), 'C:/');
+    expect(context.rootPrefix(r'\\server\share\a\b'), r'\\server\share');
+    expect(context.rootPrefix(r'\a\b'), r'\');
+    expect(context.rootPrefix(r'/a/b'), r'/');
+    expect(context.rootPrefix(r'\'), r'\');
+    expect(context.rootPrefix(r'/'), r'/');
   });
 
   test('dirname', () {
-    expect(builder.dirname(r''), '.');
-    expect(builder.dirname(r'a'), '.');
-    expect(builder.dirname(r'a\b'), 'a');
-    expect(builder.dirname(r'a\b\c'), r'a\b');
-    expect(builder.dirname(r'a\b.c'), 'a');
-    expect(builder.dirname(r'a\'), '.');
-    expect(builder.dirname('a/'), '.');
-    expect(builder.dirname(r'a\.'), 'a');
-    expect(builder.dirname(r'a\b/c'), r'a\b');
-    expect(builder.dirname(r'C:\a'), r'C:\');
-    expect(builder.dirname(r'C:\\\a'), r'C:\');
-    expect(builder.dirname(r'C:\'), r'C:\');
-    expect(builder.dirname(r'C:\\\'), r'C:\');
-    expect(builder.dirname(r'a\b\'), r'a');
-    expect(builder.dirname(r'a/b\c'), 'a/b');
-    expect(builder.dirname(r'a\\'), r'.');
-    expect(builder.dirname(r'a\b\\'), 'a');
-    expect(builder.dirname(r'a\\b'), 'a');
-    expect(builder.dirname(r'foo bar\gule fisk'), 'foo bar');
-    expect(builder.dirname(r'\\server\share'), r'\\server\share');
-    expect(builder.dirname(r'\\server\share\dir'), r'\\server\share');
-    expect(builder.dirname(r'\a'), r'\');
-    expect(builder.dirname(r'/a'), r'/');
-    expect(builder.dirname(r'\'), r'\');
-    expect(builder.dirname(r'/'), r'/');
+    expect(context.dirname(r''), '.');
+    expect(context.dirname(r'a'), '.');
+    expect(context.dirname(r'a\b'), 'a');
+    expect(context.dirname(r'a\b\c'), r'a\b');
+    expect(context.dirname(r'a\b.c'), 'a');
+    expect(context.dirname(r'a\'), '.');
+    expect(context.dirname('a/'), '.');
+    expect(context.dirname(r'a\.'), 'a');
+    expect(context.dirname(r'a\b/c'), r'a\b');
+    expect(context.dirname(r'C:\a'), r'C:\');
+    expect(context.dirname(r'C:\\\a'), r'C:\');
+    expect(context.dirname(r'C:\'), r'C:\');
+    expect(context.dirname(r'C:\\\'), r'C:\');
+    expect(context.dirname(r'a\b\'), r'a');
+    expect(context.dirname(r'a/b\c'), 'a/b');
+    expect(context.dirname(r'a\\'), r'.');
+    expect(context.dirname(r'a\b\\'), 'a');
+    expect(context.dirname(r'a\\b'), 'a');
+    expect(context.dirname(r'foo bar\gule fisk'), 'foo bar');
+    expect(context.dirname(r'\\server\share'), r'\\server\share');
+    expect(context.dirname(r'\\server\share\dir'), r'\\server\share');
+    expect(context.dirname(r'\a'), r'\');
+    expect(context.dirname(r'/a'), r'/');
+    expect(context.dirname(r'\'), r'\');
+    expect(context.dirname(r'/'), r'/');
   });
 
   test('basename', () {
-    expect(builder.basename(r''), '');
-    expect(builder.basename(r'.'), '.');
-    expect(builder.basename(r'..'), '..');
-    expect(builder.basename(r'.hest'), '.hest');
-    expect(builder.basename(r'a'), 'a');
-    expect(builder.basename(r'a\b'), 'b');
-    expect(builder.basename(r'a\b\c'), 'c');
-    expect(builder.basename(r'a\b.c'), 'b.c');
-    expect(builder.basename(r'a\'), 'a');
-    expect(builder.basename(r'a/'), 'a');
-    expect(builder.basename(r'a\.'), '.');
-    expect(builder.basename(r'a\b/c'), r'c');
-    expect(builder.basename(r'C:\a'), 'a');
-    expect(builder.basename(r'C:\'), r'C:\');
-    expect(builder.basename(r'a\b\'), 'b');
-    expect(builder.basename(r'a/b\c'), 'c');
-    expect(builder.basename(r'a\\'), 'a');
-    expect(builder.basename(r'a\b\\'), 'b');
-    expect(builder.basename(r'a\\b'), 'b');
-    expect(builder.basename(r'a\\b'), 'b');
-    expect(builder.basename(r'a\fisk hest.ma pa'), 'fisk hest.ma pa');
-    expect(builder.basename(r'\\server\share'), r'\\server\share');
-    expect(builder.basename(r'\\server\share\dir'), r'dir');
-    expect(builder.basename(r'\a'), r'a');
-    expect(builder.basename(r'/a'), r'a');
-    expect(builder.basename(r'\'), r'\');
-    expect(builder.basename(r'/'), r'/');
+    expect(context.basename(r''), '');
+    expect(context.basename(r'.'), '.');
+    expect(context.basename(r'..'), '..');
+    expect(context.basename(r'.hest'), '.hest');
+    expect(context.basename(r'a'), 'a');
+    expect(context.basename(r'a\b'), 'b');
+    expect(context.basename(r'a\b\c'), 'c');
+    expect(context.basename(r'a\b.c'), 'b.c');
+    expect(context.basename(r'a\'), 'a');
+    expect(context.basename(r'a/'), 'a');
+    expect(context.basename(r'a\.'), '.');
+    expect(context.basename(r'a\b/c'), r'c');
+    expect(context.basename(r'C:\a'), 'a');
+    expect(context.basename(r'C:\'), r'C:\');
+    expect(context.basename(r'a\b\'), 'b');
+    expect(context.basename(r'a/b\c'), 'c');
+    expect(context.basename(r'a\\'), 'a');
+    expect(context.basename(r'a\b\\'), 'b');
+    expect(context.basename(r'a\\b'), 'b');
+    expect(context.basename(r'a\\b'), 'b');
+    expect(context.basename(r'a\fisk hest.ma pa'), 'fisk hest.ma pa');
+    expect(context.basename(r'\\server\share'), r'\\server\share');
+    expect(context.basename(r'\\server\share\dir'), r'dir');
+    expect(context.basename(r'\a'), r'a');
+    expect(context.basename(r'/a'), r'a');
+    expect(context.basename(r'\'), r'\');
+    expect(context.basename(r'/'), r'/');
   });
 
   test('basenameWithoutExtension', () {
-    expect(builder.basenameWithoutExtension(''), '');
-    expect(builder.basenameWithoutExtension('.'), '.');
-    expect(builder.basenameWithoutExtension('..'), '..');
-    expect(builder.basenameWithoutExtension('.hest'), '.hest');
-    expect(builder.basenameWithoutExtension('a'), 'a');
-    expect(builder.basenameWithoutExtension(r'a\b'), 'b');
-    expect(builder.basenameWithoutExtension(r'a\b\c'), 'c');
-    expect(builder.basenameWithoutExtension(r'a\b.c'), 'b');
-    expect(builder.basenameWithoutExtension(r'a\'), 'a');
-    expect(builder.basenameWithoutExtension(r'a\.'), '.');
-    expect(builder.basenameWithoutExtension(r'a\b/c'), r'c');
-    expect(builder.basenameWithoutExtension(r'a\.bashrc'), '.bashrc');
-    expect(builder.basenameWithoutExtension(r'a\b\c.d.e'), 'c.d');
-    expect(builder.basenameWithoutExtension(r'a\\'), 'a');
-    expect(builder.basenameWithoutExtension(r'a\b\\'), 'b');
-    expect(builder.basenameWithoutExtension(r'a\\b'), 'b');
-    expect(builder.basenameWithoutExtension(r'a\b.c\'), 'b');
-    expect(builder.basenameWithoutExtension(r'a\b.c\\'), 'b');
-    expect(builder.basenameWithoutExtension(r'C:\f h.ma pa.f s'), 'f h.ma pa');
+    expect(context.basenameWithoutExtension(''), '');
+    expect(context.basenameWithoutExtension('.'), '.');
+    expect(context.basenameWithoutExtension('..'), '..');
+    expect(context.basenameWithoutExtension('.hest'), '.hest');
+    expect(context.basenameWithoutExtension('a'), 'a');
+    expect(context.basenameWithoutExtension(r'a\b'), 'b');
+    expect(context.basenameWithoutExtension(r'a\b\c'), 'c');
+    expect(context.basenameWithoutExtension(r'a\b.c'), 'b');
+    expect(context.basenameWithoutExtension(r'a\'), 'a');
+    expect(context.basenameWithoutExtension(r'a\.'), '.');
+    expect(context.basenameWithoutExtension(r'a\b/c'), r'c');
+    expect(context.basenameWithoutExtension(r'a\.bashrc'), '.bashrc');
+    expect(context.basenameWithoutExtension(r'a\b\c.d.e'), 'c.d');
+    expect(context.basenameWithoutExtension(r'a\\'), 'a');
+    expect(context.basenameWithoutExtension(r'a\b\\'), 'b');
+    expect(context.basenameWithoutExtension(r'a\\b'), 'b');
+    expect(context.basenameWithoutExtension(r'a\b.c\'), 'b');
+    expect(context.basenameWithoutExtension(r'a\b.c\\'), 'b');
+    expect(context.basenameWithoutExtension(r'C:\f h.ma pa.f s'), 'f h.ma pa');
   });
 
   test('isAbsolute', () {
-    expect(builder.isAbsolute(''), false);
-    expect(builder.isAbsolute('.'), false);
-    expect(builder.isAbsolute('..'), false);
-    expect(builder.isAbsolute('a'), false);
-    expect(builder.isAbsolute(r'a\b'), false);
-    expect(builder.isAbsolute(r'\a\b'), true);
-    expect(builder.isAbsolute(r'\'), true);
-    expect(builder.isAbsolute(r'/a/b'), true);
-    expect(builder.isAbsolute(r'/'), true);
-    expect(builder.isAbsolute('~'), false);
-    expect(builder.isAbsolute('.'), false);
-    expect(builder.isAbsolute(r'..\a'), false);
-    expect(builder.isAbsolute(r'a:/a\b'), true);
-    expect(builder.isAbsolute(r'D:/a/b'), true);
-    expect(builder.isAbsolute(r'c:\'), true);
-    expect(builder.isAbsolute(r'B:\'), true);
-    expect(builder.isAbsolute(r'c:\a'), true);
-    expect(builder.isAbsolute(r'C:\a'), true);
-    expect(builder.isAbsolute(r'\\server\share'), true);
-    expect(builder.isAbsolute(r'\\server\share\path'), true);
+    expect(context.isAbsolute(''), false);
+    expect(context.isAbsolute('.'), false);
+    expect(context.isAbsolute('..'), false);
+    expect(context.isAbsolute('a'), false);
+    expect(context.isAbsolute(r'a\b'), false);
+    expect(context.isAbsolute(r'\a\b'), true);
+    expect(context.isAbsolute(r'\'), true);
+    expect(context.isAbsolute(r'/a/b'), true);
+    expect(context.isAbsolute(r'/'), true);
+    expect(context.isAbsolute('~'), false);
+    expect(context.isAbsolute('.'), false);
+    expect(context.isAbsolute(r'..\a'), false);
+    expect(context.isAbsolute(r'a:/a\b'), true);
+    expect(context.isAbsolute(r'D:/a/b'), true);
+    expect(context.isAbsolute(r'c:\'), true);
+    expect(context.isAbsolute(r'B:\'), true);
+    expect(context.isAbsolute(r'c:\a'), true);
+    expect(context.isAbsolute(r'C:\a'), true);
+    expect(context.isAbsolute(r'\\server\share'), true);
+    expect(context.isAbsolute(r'\\server\share\path'), true);
   });
 
   test('isRelative', () {
-    expect(builder.isRelative(''), true);
-    expect(builder.isRelative('.'), true);
-    expect(builder.isRelative('..'), true);
-    expect(builder.isRelative('a'), true);
-    expect(builder.isRelative(r'a\b'), true);
-    expect(builder.isRelative(r'\a\b'), false);
-    expect(builder.isRelative(r'\'), false);
-    expect(builder.isRelative(r'/a/b'), false);
-    expect(builder.isRelative(r'/'), false);
-    expect(builder.isRelative('~'), true);
-    expect(builder.isRelative('.'), true);
-    expect(builder.isRelative(r'..\a'), true);
-    expect(builder.isRelative(r'a:/a\b'), false);
-    expect(builder.isRelative(r'D:/a/b'), false);
-    expect(builder.isRelative(r'c:\'), false);
-    expect(builder.isRelative(r'B:\'), false);
-    expect(builder.isRelative(r'c:\a'), false);
-    expect(builder.isRelative(r'C:\a'), false);
-    expect(builder.isRelative(r'\\server\share'), false);
-    expect(builder.isRelative(r'\\server\share\path'), false);
+    expect(context.isRelative(''), true);
+    expect(context.isRelative('.'), true);
+    expect(context.isRelative('..'), true);
+    expect(context.isRelative('a'), true);
+    expect(context.isRelative(r'a\b'), true);
+    expect(context.isRelative(r'\a\b'), false);
+    expect(context.isRelative(r'\'), false);
+    expect(context.isRelative(r'/a/b'), false);
+    expect(context.isRelative(r'/'), false);
+    expect(context.isRelative('~'), true);
+    expect(context.isRelative('.'), true);
+    expect(context.isRelative(r'..\a'), true);
+    expect(context.isRelative(r'a:/a\b'), false);
+    expect(context.isRelative(r'D:/a/b'), false);
+    expect(context.isRelative(r'c:\'), false);
+    expect(context.isRelative(r'B:\'), false);
+    expect(context.isRelative(r'c:\a'), false);
+    expect(context.isRelative(r'C:\a'), false);
+    expect(context.isRelative(r'\\server\share'), false);
+    expect(context.isRelative(r'\\server\share\path'), false);
   });
 
   test('isRootRelative', () {
-    expect(builder.isRootRelative(''), false);
-    expect(builder.isRootRelative('.'), false);
-    expect(builder.isRootRelative('..'), false);
-    expect(builder.isRootRelative('a'), false);
-    expect(builder.isRootRelative(r'a\b'), false);
-    expect(builder.isRootRelative(r'\a\b'), true);
-    expect(builder.isRootRelative(r'\'), true);
-    expect(builder.isRootRelative(r'/a/b'), true);
-    expect(builder.isRootRelative(r'/'), true);
-    expect(builder.isRootRelative('~'), false);
-    expect(builder.isRootRelative('.'), false);
-    expect(builder.isRootRelative(r'..\a'), false);
-    expect(builder.isRootRelative(r'a:/a\b'), false);
-    expect(builder.isRootRelative(r'D:/a/b'), false);
-    expect(builder.isRootRelative(r'c:\'), false);
-    expect(builder.isRootRelative(r'B:\'), false);
-    expect(builder.isRootRelative(r'c:\a'), false);
-    expect(builder.isRootRelative(r'C:\a'), false);
-    expect(builder.isRootRelative(r'\\server\share'), false);
-    expect(builder.isRootRelative(r'\\server\share\path'), false);
+    expect(context.isRootRelative(''), false);
+    expect(context.isRootRelative('.'), false);
+    expect(context.isRootRelative('..'), false);
+    expect(context.isRootRelative('a'), false);
+    expect(context.isRootRelative(r'a\b'), false);
+    expect(context.isRootRelative(r'\a\b'), true);
+    expect(context.isRootRelative(r'\'), true);
+    expect(context.isRootRelative(r'/a/b'), true);
+    expect(context.isRootRelative(r'/'), true);
+    expect(context.isRootRelative('~'), false);
+    expect(context.isRootRelative('.'), false);
+    expect(context.isRootRelative(r'..\a'), false);
+    expect(context.isRootRelative(r'a:/a\b'), false);
+    expect(context.isRootRelative(r'D:/a/b'), false);
+    expect(context.isRootRelative(r'c:\'), false);
+    expect(context.isRootRelative(r'B:\'), false);
+    expect(context.isRootRelative(r'c:\a'), false);
+    expect(context.isRootRelative(r'C:\a'), false);
+    expect(context.isRootRelative(r'\\server\share'), false);
+    expect(context.isRootRelative(r'\\server\share\path'), false);
   });
 
   group('join', () {
     test('allows up to eight parts', () {
-      expect(builder.join('a'), 'a');
-      expect(builder.join('a', 'b'), r'a\b');
-      expect(builder.join('a', 'b', 'c'), r'a\b\c');
-      expect(builder.join('a', 'b', 'c', 'd'), r'a\b\c\d');
-      expect(builder.join('a', 'b', 'c', 'd', 'e'), r'a\b\c\d\e');
-      expect(builder.join('a', 'b', 'c', 'd', 'e', 'f'), r'a\b\c\d\e\f');
-      expect(builder.join('a', 'b', 'c', 'd', 'e', 'f', 'g'), r'a\b\c\d\e\f\g');
-      expect(builder.join('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'),
+      expect(context.join('a'), 'a');
+      expect(context.join('a', 'b'), r'a\b');
+      expect(context.join('a', 'b', 'c'), r'a\b\c');
+      expect(context.join('a', 'b', 'c', 'd'), r'a\b\c\d');
+      expect(context.join('a', 'b', 'c', 'd', 'e'), r'a\b\c\d\e');
+      expect(context.join('a', 'b', 'c', 'd', 'e', 'f'), r'a\b\c\d\e\f');
+      expect(context.join('a', 'b', 'c', 'd', 'e', 'f', 'g'), r'a\b\c\d\e\f\g');
+      expect(context.join('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'),
           r'a\b\c\d\e\f\g\h');
     });
 
     test('does not add separator if a part ends or begins in one', () {
-      expect(builder.join(r'a\', 'b', r'c\', 'd'), r'a\b\c\d');
-      expect(builder.join('a/', 'b'), r'a/b');
+      expect(context.join(r'a\', 'b', r'c\', 'd'), r'a\b\c\d');
+      expect(context.join('a/', 'b'), r'a/b');
     });
 
     test('ignores parts before an absolute path', () {
-      expect(builder.join('a', r'\b', r'\c', 'd'), r'\c\d');
-      expect(builder.join('a', '/b', '/c', 'd'), r'/c\d');
-      expect(builder.join('a', r'c:\b', 'c', 'd'), r'c:\b\c\d');
-      expect(builder.join('a', r'\\b\c', r'\\d\e', 'f'), r'\\d\e\f');
-      expect(builder.join('a', r'c:\b', r'\c', 'd'), r'c:\c\d');
-      expect(builder.join('a', r'\\b\c\d', r'\e', 'f'), r'\\b\c\e\f');
+      expect(context.join('a', r'\b', r'\c', 'd'), r'\c\d');
+      expect(context.join('a', '/b', '/c', 'd'), r'/c\d');
+      expect(context.join('a', r'c:\b', 'c', 'd'), r'c:\b\c\d');
+      expect(context.join('a', r'\\b\c', r'\\d\e', 'f'), r'\\d\e\f');
+      expect(context.join('a', r'c:\b', r'\c', 'd'), r'c:\c\d');
+      expect(context.join('a', r'\\b\c\d', r'\e', 'f'), r'\\b\c\e\f');
     });
 
     test('ignores trailing nulls', () {
-      expect(builder.join('a', null), equals('a'));
-      expect(builder.join('a', 'b', 'c', null, null), equals(r'a\b\c'));
+      expect(context.join('a', null), equals('a'));
+      expect(context.join('a', 'b', 'c', null, null), equals(r'a\b\c'));
     });
 
     test('ignores empty strings', () {
-      expect(builder.join(''), '');
-      expect(builder.join('', ''), '');
-      expect(builder.join('', 'a'), 'a');
-      expect(builder.join('a', '', 'b', '', '', '', 'c'), r'a\b\c');
-      expect(builder.join('a', 'b', ''), r'a\b');
+      expect(context.join(''), '');
+      expect(context.join('', ''), '');
+      expect(context.join('', 'a'), 'a');
+      expect(context.join('a', '', 'b', '', '', '', 'c'), r'a\b\c');
+      expect(context.join('a', 'b', ''), r'a\b');
     });
 
     test('disallows intermediate nulls', () {
-      expect(() => builder.join('a', null, 'b'), throwsArgumentError);
-      expect(() => builder.join(null, 'a'), throwsArgumentError);
+      expect(() => context.join('a', null, 'b'), throwsArgumentError);
+      expect(() => context.join(null, 'a'), throwsArgumentError);
     });
 
     test('join does not modify internal ., .., or trailing separators', () {
-      expect(builder.join('a/', 'b/c/'), 'a/b/c/');
-      expect(builder.join(r'a\b\./c\..\\', r'd\..\.\..\\e\f\\'),
+      expect(context.join('a/', 'b/c/'), 'a/b/c/');
+      expect(context.join(r'a\b\./c\..\\', r'd\..\.\..\\e\f\\'),
              r'a\b\./c\..\\d\..\.\..\\e\f\\');
-      expect(builder.join(r'a\b', r'c\..\..\..\..'), r'a\b\c\..\..\..\..');
-      expect(builder.join(r'a', 'b${builder.separator}'), r'a\b\');
+      expect(context.join(r'a\b', r'c\..\..\..\..'), r'a\b\c\..\..\..\..');
+      expect(context.join(r'a', 'b${context.separator}'), r'a\b\');
     });
   });
 
   group('joinAll', () {
     test('allows more than eight parts', () {
-      expect(builder.joinAll(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']),
+      expect(context.joinAll(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i']),
           r'a\b\c\d\e\f\g\h\i');
     });
 
     test('does not add separator if a part ends or begins in one', () {
-      expect(builder.joinAll([r'a\', 'b', r'c\', 'd']), r'a\b\c\d');
-      expect(builder.joinAll(['a/', 'b']), r'a/b');
+      expect(context.joinAll([r'a\', 'b', r'c\', 'd']), r'a\b\c\d');
+      expect(context.joinAll(['a/', 'b']), r'a/b');
     });
 
     test('ignores parts before an absolute path', () {
-      expect(builder.joinAll(['a', r'\b', r'\c', 'd']), r'\c\d');
-      expect(builder.joinAll(['a', '/b', '/c', 'd']), r'/c\d');
-      expect(builder.joinAll(['a', r'c:\b', 'c', 'd']), r'c:\b\c\d');
-      expect(builder.joinAll(['a', r'\\b\c', r'\\d\e', 'f']), r'\\d\e\f');
-      expect(builder.joinAll(['a', r'c:\b', r'\c', 'd']), r'c:\c\d');
-      expect(builder.joinAll(['a', r'\\b\c\d', r'\e', 'f']), r'\\b\c\e\f');
+      expect(context.joinAll(['a', r'\b', r'\c', 'd']), r'\c\d');
+      expect(context.joinAll(['a', '/b', '/c', 'd']), r'/c\d');
+      expect(context.joinAll(['a', r'c:\b', 'c', 'd']), r'c:\b\c\d');
+      expect(context.joinAll(['a', r'\\b\c', r'\\d\e', 'f']), r'\\d\e\f');
+      expect(context.joinAll(['a', r'c:\b', r'\c', 'd']), r'c:\c\d');
+      expect(context.joinAll(['a', r'\\b\c\d', r'\e', 'f']), r'\\b\c\e\f');
     });
   });
 
   group('split', () {
     test('simple cases', () {
-      expect(builder.split(''), []);
-      expect(builder.split('.'), ['.']);
-      expect(builder.split('..'), ['..']);
-      expect(builder.split('foo'), equals(['foo']));
-      expect(builder.split(r'foo\bar.txt'), equals(['foo', 'bar.txt']));
-      expect(builder.split(r'foo\bar/baz'), equals(['foo', 'bar', 'baz']));
-      expect(builder.split(r'foo\..\bar\.\baz'),
+      expect(context.split(''), []);
+      expect(context.split('.'), ['.']);
+      expect(context.split('..'), ['..']);
+      expect(context.split('foo'), equals(['foo']));
+      expect(context.split(r'foo\bar.txt'), equals(['foo', 'bar.txt']));
+      expect(context.split(r'foo\bar/baz'), equals(['foo', 'bar', 'baz']));
+      expect(context.split(r'foo\..\bar\.\baz'),
           equals(['foo', '..', 'bar', '.', 'baz']));
-      expect(builder.split(r'foo\\bar\\\baz'), equals(['foo', 'bar', 'baz']));
-      expect(builder.split(r'foo\/\baz'), equals(['foo', 'baz']));
-      expect(builder.split('.'), equals(['.']));
-      expect(builder.split(''), equals([]));
-      expect(builder.split('foo/'), equals(['foo']));
-      expect(builder.split(r'C:\'), equals([r'C:\']));
+      expect(context.split(r'foo\\bar\\\baz'), equals(['foo', 'bar', 'baz']));
+      expect(context.split(r'foo\/\baz'), equals(['foo', 'baz']));
+      expect(context.split('.'), equals(['.']));
+      expect(context.split(''), equals([]));
+      expect(context.split('foo/'), equals(['foo']));
+      expect(context.split(r'C:\'), equals([r'C:\']));
     });
 
     test('includes the root for absolute paths', () {
-      expect(builder.split(r'C:\foo\bar\baz'),
+      expect(context.split(r'C:\foo\bar\baz'),
           equals([r'C:\', 'foo', 'bar', 'baz']));
-      expect(builder.split(r'C:\\'), equals([r'C:\']));
-
-      expect(builder.split(r'\\server\share\foo\bar\baz'),
+      expect(context.split(r'C:\\'), equals([r'C:\']));
+
+      expect(context.split(r'\\server\share\foo\bar\baz'),
           equals([r'\\server\share', 'foo', 'bar', 'baz']));
-      expect(builder.split(r'\\server\share'), equals([r'\\server\share']));
-
-      expect(builder.split(r'\foo\bar\baz'),
+      expect(context.split(r'\\server\share'), equals([r'\\server\share']));
+
+      expect(context.split(r'\foo\bar\baz'),
           equals([r'\', 'foo', 'bar', 'baz']));
-      expect(builder.split(r'\'), equals([r'\']));
+      expect(context.split(r'\'), equals([r'\']));
     });
   });
 
   group('normalize', () {
     test('simple cases', () {
-      expect(builder.normalize(''), '.');
-      expect(builder.normalize('.'), '.');
-      expect(builder.normalize('..'), '..');
-      expect(builder.normalize('a'), 'a');
-      expect(builder.normalize('/a/b'), r'\a\b');
-      expect(builder.normalize(r'\'), r'\');
-      expect(builder.normalize(r'\a\b'), r'\a\b');
-      expect(builder.normalize('/'), r'\');
-      expect(builder.normalize('C:/'), r'C:\');
-      expect(builder.normalize(r'C:\'), r'C:\');
-      expect(builder.normalize(r'\\server\share'), r'\\server\share');
-      expect(builder.normalize('a\\.\\\xc5\u0bf8-;\u{1f085}\u{00}\\c\\d\\..\\'),
+      expect(context.normalize(''), '.');
+      expect(context.normalize('.'), '.');
+      expect(context.normalize('..'), '..');
+      expect(context.normalize('a'), 'a');
+      expect(context.normalize('/a/b'), r'\a\b');
+      expect(context.normalize(r'\'), r'\');
+      expect(context.normalize(r'\a\b'), r'\a\b');
+      expect(context.normalize('/'), r'\');
+      expect(context.normalize('C:/'), r'C:\');
+      expect(context.normalize(r'C:\'), r'C:\');
+      expect(context.normalize(r'\\server\share'), r'\\server\share');
+      expect(context.normalize('a\\.\\\xc5\u0bf8-;\u{1f085}\u{00}\\c\\d\\..\\'),
              'a\\\xc5\u0bf8-;\u{1f085}\u{00}\x5cc');
     });
 
     test('collapses redundant separators', () {
-      expect(builder.normalize(r'a\b\c'), r'a\b\c');
-      expect(builder.normalize(r'a\\b\\\c\\\\d'), r'a\b\c\d');
+      expect(context.normalize(r'a\b\c'), r'a\b\c');
+      expect(context.normalize(r'a\\b\\\c\\\\d'), r'a\b\c\d');
     });
 
     test('eliminates "." parts', () {
-      expect(builder.normalize(r'.\'), '.');
-      expect(builder.normalize(r'c:\.'), r'c:\');
-      expect(builder.normalize(r'B:\.\'), r'B:\');
-      expect(builder.normalize(r'\\server\share\.'), r'\\server\share');
-      expect(builder.normalize(r'.\.'), '.');
-      expect(builder.normalize(r'a\.\b'), r'a\b');
-      expect(builder.normalize(r'a\.b\c'), r'a\.b\c');
-      expect(builder.normalize(r'a\./.\b\.\c'), r'a\b\c');
-      expect(builder.normalize(r'.\./a'), 'a');
-      expect(builder.normalize(r'a/.\.'), 'a');
-      expect(builder.normalize(r'\.'), r'\');
-      expect(builder.normalize('/.'), r'\');
+      expect(context.normalize(r'.\'), '.');
+      expect(context.normalize(r'c:\.'), r'c:\');
+      expect(context.normalize(r'B:\.\'), r'B:\');
+      expect(context.normalize(r'\\server\share\.'), r'\\server\share');
+      expect(context.normalize(r'.\.'), '.');
+      expect(context.normalize(r'a\.\b'), r'a\b');
+      expect(context.normalize(r'a\.b\c'), r'a\.b\c');
+      expect(context.normalize(r'a\./.\b\.\c'), r'a\b\c');
+      expect(context.normalize(r'.\./a'), 'a');
+      expect(context.normalize(r'a/.\.'), 'a');
+      expect(context.normalize(r'\.'), r'\');
+      expect(context.normalize('/.'), r'\');
     });
 
     test('eliminates ".." parts', () {
-      expect(builder.normalize('..'), '..');
-      expect(builder.normalize(r'..\'), '..');
-      expect(builder.normalize(r'..\..\..'), r'..\..\..');
-      expect(builder.normalize(r'../..\..\'), r'..\..\..');
-      expect(builder.normalize(r'\\server\share\..'), r'\\server\share');
-      expect(builder.normalize(r'\\server\share\..\../..\a'),
+      expect(context.normalize('..'), '..');
+      expect(context.normalize(r'..\'), '..');
+      expect(context.normalize(r'..\..\..'), r'..\..\..');
+      expect(context.normalize(r'../..\..\'), r'..\..\..');
+      expect(context.normalize(r'\\server\share\..'), r'\\server\share');
+      expect(context.normalize(r'\\server\share\..\../..\a'),
           r'\\server\share\a');
-      expect(builder.normalize(r'c:\..'), r'c:\');
-      expect(builder.normalize(r'A:/..\..\..'), r'A:\');
-      expect(builder.normalize(r'b:\..\..\..\a'), r'b:\a');
-      expect(builder.normalize(r'b:\r\..\..\..\a\c\.\..'), r'b:\a');
-      expect(builder.normalize(r'a\..'), '.');
-      expect(builder.normalize(r'..\a'), r'..\a');
-      expect(builder.normalize(r'c:\..\a'), r'c:\a');
-      expect(builder.normalize(r'\..\a'), r'\a');
-      expect(builder.normalize(r'a\b\..'), 'a');
-      expect(builder.normalize(r'..\a\b\..'), r'..\a');
-      expect(builder.normalize(r'a\..\b'), 'b');
-      expect(builder.normalize(r'a\.\..\b'), 'b');
-      expect(builder.normalize(r'a\b\c\..\..\d\e\..'), r'a\d');
-      expect(builder.normalize(r'a\b\..\..\..\..\c'), r'..\..\c');
-      expect(builder.normalize(r'a/b/c/../../..d/./.e/f././'), r'a\..d\.e\f.');
+      expect(context.normalize(r'c:\..'), r'c:\');
+      expect(context.normalize(r'A:/..\..\..'), r'A:\');
+      expect(context.normalize(r'b:\..\..\..\a'), r'b:\a');
+      expect(context.normalize(r'b:\r\..\..\..\a\c\.\..'), r'b:\a');
+      expect(context.normalize(r'a\..'), '.');
+      expect(context.normalize(r'..\a'), r'..\a');
+      expect(context.normalize(r'c:\..\a'), r'c:\a');
+      expect(context.normalize(r'\..\a'), r'\a');
+      expect(context.normalize(r'a\b\..'), 'a');
+      expect(context.normalize(r'..\a\b\..'), r'..\a');
+      expect(context.normalize(r'a\..\b'), 'b');
+      expect(context.normalize(r'a\.\..\b'), 'b');
+      expect(context.normalize(r'a\b\c\..\..\d\e\..'), r'a\d');
+      expect(context.normalize(r'a\b\..\..\..\..\c'), r'..\..\c');
+      expect(context.normalize(r'a/b/c/../../..d/./.e/f././'), r'a\..d\.e\f.');
     });
 
     test('removes trailing separators', () {
-      expect(builder.normalize(r'.\'), '.');
-      expect(builder.normalize(r'.\\'), '.');
-      expect(builder.normalize(r'a/'), 'a');
-      expect(builder.normalize(r'a\b\'), r'a\b');
-      expect(builder.normalize(r'a\b\\\'), r'a\b');
+      expect(context.normalize(r'.\'), '.');
+      expect(context.normalize(r'.\\'), '.');
+      expect(context.normalize(r'a/'), 'a');
+      expect(context.normalize(r'a\b\'), r'a\b');
+      expect(context.normalize(r'a\b\\\'), r'a\b');
     });
 
     test('normalizes separators', () {
-      expect(builder.normalize(r'a/b\c'), r'a\b\c');
+      expect(context.normalize(r'a/b\c'), r'a\b\c');
     });
   });
 
   group('relative', () {
     group('from absolute root', () {
       test('given absolute path in root', () {
-        expect(builder.relative(r'C:\'), r'..\..');
-        expect(builder.relative(r'C:\root'), '..');
-        expect(builder.relative(r'\root'), '..');
-        expect(builder.relative(r'C:\root\path'), '.');
-        expect(builder.relative(r'\root\path'), '.');
-        expect(builder.relative(r'C:\root\path\a'), 'a');
-        expect(builder.relative(r'\root\path\a'), 'a');
-        expect(builder.relative(r'C:\root\path\a\b.txt'), r'a\b.txt');
-        expect(builder.relative(r'C:\root\a\b.txt'), r'..\a\b.txt');
-        expect(builder.relative(r'C:/'), r'..\..');
-        expect(builder.relative(r'C:/root'), '..');
-        expect(builder.relative(r'c:\'), r'..\..');
-        expect(builder.relative(r'c:\root'), '..');
+        expect(context.relative(r'C:\'), r'..\..');
+        expect(context.relative(r'C:\root'), '..');
+        expect(context.relative(r'\root'), '..');
+        expect(context.relative(r'C:\root\path'), '.');
+        expect(context.relative(r'\root\path'), '.');
+        expect(context.relative(r'C:\root\path\a'), 'a');
+        expect(context.relative(r'\root\path\a'), 'a');
+        expect(context.relative(r'C:\root\path\a\b.txt'), r'a\b.txt');
+        expect(context.relative(r'C:\root\a\b.txt'), r'..\a\b.txt');
+        expect(context.relative(r'C:/'), r'..\..');
+        expect(context.relative(r'C:/root'), '..');
+        expect(context.relative(r'c:\'), r'..\..');
+        expect(context.relative(r'c:\root'), '..');
       });
 
       test('given absolute path outside of root', () {
-        expect(builder.relative(r'C:\a\b'), r'..\..\a\b');
-        expect(builder.relative(r'\a\b'), r'..\..\a\b');
-        expect(builder.relative(r'C:\root\path\a'), 'a');
-        expect(builder.relative(r'C:\root\path\a\b.txt'), r'a\b.txt');
-        expect(builder.relative(r'C:\root\a\b.txt'), r'..\a\b.txt');
-        expect(builder.relative(r'C:/a/b'), r'..\..\a\b');
-        expect(builder.relative(r'C:/root/path/a'), 'a');
-        expect(builder.relative(r'c:\a\b'), r'..\..\a\b');
-        expect(builder.relative(r'c:\root\path\a'), 'a');
+        expect(context.relative(r'C:\a\b'), r'..\..\a\b');
+        expect(context.relative(r'\a\b'), r'..\..\a\b');
+        expect(context.relative(r'C:\root\path\a'), 'a');
+        expect(context.relative(r'C:\root\path\a\b.txt'), r'a\b.txt');
+        expect(context.relative(r'C:\root\a\b.txt'), r'..\a\b.txt');
+        expect(context.relative(r'C:/a/b'), r'..\..\a\b');
+        expect(context.relative(r'C:/root/path/a'), 'a');
+        expect(context.relative(r'c:\a\b'), r'..\..\a\b');
+        expect(context.relative(r'c:\root\path\a'), 'a');
       });
 
       test('given absolute path on different drive', () {
-        expect(builder.relative(r'D:\a\b'), r'D:\a\b');
+        expect(context.relative(r'D:\a\b'), r'D:\a\b');
       });
 
       test('given relative path', () {
         // The path is considered relative to the root, so it basically just
         // normalizes.
-        expect(builder.relative(''), '.');
-        expect(builder.relative('.'), '.');
-        expect(builder.relative('a'), 'a');
-        expect(builder.relative(r'a\b.txt'), r'a\b.txt');
-        expect(builder.relative(r'..\a\b.txt'), r'..\a\b.txt');
-        expect(builder.relative(r'a\.\b\..\c.txt'), r'a\c.txt');
+        expect(context.relative(''), '.');
+        expect(context.relative('.'), '.');
+        expect(context.relative('a'), 'a');
+        expect(context.relative(r'a\b.txt'), r'a\b.txt');
+        expect(context.relative(r'..\a\b.txt'), r'..\a\b.txt');
+        expect(context.relative(r'a\.\b\..\c.txt'), r'a\c.txt');
       });
 
       // Regression
       test('from root-only path', () {
-        expect(builder.relative(r'C:\', from: r'C:\'), '.');
-        expect(builder.relative(r'C:\root\path', from: r'C:\'), r'root\path');
+        expect(context.relative(r'C:\', from: r'C:\'), '.');
+        expect(context.relative(r'C:\root\path', from: r'C:\'), r'root\path');
       });
     });
 
     group('from relative root', () {
-      var r = new path.Builder(style: path.Style.windows, root: r'foo\bar');
+      var r = new path.Context(style: path.Style.windows, current: r'foo\bar');
 
       test('given absolute path', () {
         expect(r.relative(r'C:\'), equals(r'C:\'));
         expect(r.relative(r'C:\a\b'), equals(r'C:\a\b'));
         expect(r.relative(r'\'), equals(r'\'));
         expect(r.relative(r'\a\b'), equals(r'\a\b'));
       });
 
       test('given relative path', () {
         // The path is considered relative to the root, so it basically just
         // normalizes.
         expect(r.relative(''), '.');
         expect(r.relative('.'), '.');
         expect(r.relative('..'), '..');
         expect(r.relative('a'), 'a');
         expect(r.relative(r'a\b.txt'), r'a\b.txt');
         expect(r.relative(r'..\a/b.txt'), r'..\a\b.txt');
         expect(r.relative(r'a\./b\../c.txt'), r'a\c.txt');
       });
     });
 
     group('from root-relative root', () {
-      var r = new path.Builder(style: path.Style.windows, root: r'\foo\bar');
+      var r = new path.Context(style: path.Style.windows, current: r'\foo\bar');
 
       test('given absolute path', () {
         expect(r.relative(r'C:\'), equals(r'C:\'));
         expect(r.relative(r'C:\a\b'), equals(r'C:\a\b'));
         expect(r.relative(r'\'), equals(r'..\..'));
         expect(r.relative(r'\a\b'), equals(r'..\..\a\b'));
         expect(r.relative('/'), equals(r'..\..'));
         expect(r.relative('/a/b'), equals(r'..\..\a\b'));
       });
 
       test('given relative path', () {
         // The path is considered relative to the root, so it basically just
         // normalizes.
         expect(r.relative(''), '.');
         expect(r.relative('.'), '.');
         expect(r.relative('..'), '..');
         expect(r.relative('a'), 'a');
         expect(r.relative(r'a\b.txt'), r'a\b.txt');
         expect(r.relative(r'..\a/b.txt'), r'..\a\b.txt');
         expect(r.relative(r'a\./b\../c.txt'), r'a\c.txt');
       });
     });
 
     test('from a root with extension', () {
-      var r = new path.Builder(style: path.Style.windows, root: r'C:\dir.ext');
+      var r = new path.Context(
+          style: path.Style.windows, current: r'C:\dir.ext');
       expect(r.relative(r'C:\dir.ext\file'), 'file');
     });
 
     test('with a root parameter', () {
-      expect(builder.relative(r'C:\foo\bar\baz', from: r'C:\foo\bar'),
+      expect(context.relative(r'C:\foo\bar\baz', from: r'C:\foo\bar'),
           equals('baz'));
-      expect(builder.relative('..', from: r'C:\foo\bar'),
+      expect(context.relative('..', from: r'C:\foo\bar'),
           equals(r'..\..\root'));
-      expect(builder.relative('..', from: r'D:\foo\bar'), equals(r'C:\root'));
-      expect(builder.relative(r'C:\foo\bar\baz', from: r'foo\bar'),
+      expect(context.relative('..', from: r'D:\foo\bar'), equals(r'C:\root'));
+      expect(context.relative(r'C:\foo\bar\baz', from: r'foo\bar'),
           equals(r'..\..\..\..\foo\bar\baz'));
-      expect(builder.relative('..', from: r'foo\bar'), equals(r'..\..\..'));
+      expect(context.relative('..', from: r'foo\bar'), equals(r'..\..\..'));
     });
 
     test('with a root parameter and a relative root', () {
-      var r = new path.Builder(style: path.Style.windows, root: r'relative\root');
+      var r = new path.Context(
+          style: path.Style.windows, current: r'relative\root');
       expect(r.relative(r'C:\foo\bar\baz', from: r'C:\foo\bar'), equals('baz'));
       expect(() => r.relative('..', from: r'C:\foo\bar'), throwsPathException);
       expect(r.relative(r'C:\foo\bar\baz', from: r'foo\bar'),
           equals(r'C:\foo\bar\baz'));
       expect(r.relative('..', from: r'foo\bar'), equals(r'..\..\..'));
     });
 
     test('given absolute with different root prefix', () {
-      expect(builder.relative(r'D:\a\b'), r'D:\a\b');
-      expect(builder.relative(r'\\server\share\a\b'), r'\\server\share\a\b');
+      expect(context.relative(r'D:\a\b'), r'D:\a\b');
+      expect(context.relative(r'\\server\share\a\b'), r'\\server\share\a\b');
     });
 
     test('from a . root', () {
-      var r = new path.Builder(style: path.Style.windows, root: '.');
+      var r = new path.Context(style: path.Style.windows, current: '.');
       expect(r.relative(r'C:\foo\bar\baz'), equals(r'C:\foo\bar\baz'));
       expect(r.relative(r'foo\bar\baz'), equals(r'foo\bar\baz'));
       expect(r.relative(r'\foo\bar\baz'), equals(r'\foo\bar\baz'));
     });
   });
 
   group('isWithin', () {
     test('simple cases', () {
-      expect(builder.isWithin(r'foo\bar', r'foo\bar'), isFalse);
-      expect(builder.isWithin(r'foo\bar', r'foo\bar\baz'), isTrue);
-      expect(builder.isWithin(r'foo\bar', r'foo\baz'), isFalse);
-      expect(builder.isWithin(r'foo\bar', r'..\path\foo\bar\baz'), isTrue);
-      expect(builder.isWithin(r'C:\', r'C:\foo\bar'), isTrue);
-      expect(builder.isWithin(r'C:\', r'D:\foo\bar'), isFalse);
-      expect(builder.isWithin(r'C:\', r'\foo\bar'), isTrue);
-      expect(builder.isWithin(r'C:\foo', r'\foo\bar'), isTrue);
-      expect(builder.isWithin(r'C:\foo', r'\bar\baz'), isFalse);
-      expect(builder.isWithin(r'baz', r'C:\root\path\baz\bang'), isTrue);
-      expect(builder.isWithin(r'baz', r'C:\root\path\bang\baz'), isFalse);
+      expect(context.isWithin(r'foo\bar', r'foo\bar'), isFalse);
+      expect(context.isWithin(r'foo\bar', r'foo\bar\baz'), isTrue);
+      expect(context.isWithin(r'foo\bar', r'foo\baz'), isFalse);
+      expect(context.isWithin(r'foo\bar', r'..\path\foo\bar\baz'), isTrue);
+      expect(context.isWithin(r'C:\', r'C:\foo\bar'), isTrue);
+      expect(context.isWithin(r'C:\', r'D:\foo\bar'), isFalse);
+      expect(context.isWithin(r'C:\', r'\foo\bar'), isTrue);
+      expect(context.isWithin(r'C:\foo', r'\foo\bar'), isTrue);
+      expect(context.isWithin(r'C:\foo', r'\bar\baz'), isFalse);
+      expect(context.isWithin(r'baz', r'C:\root\path\baz\bang'), isTrue);
+      expect(context.isWithin(r'baz', r'C:\root\path\bang\baz'), isFalse);
     });
 
     test('from a relative root', () {
-      var r = new path.Builder(style: path.Style.windows, root: r'foo\bar');
-      expect(builder.isWithin('.', r'a\b\c'), isTrue);
-      expect(builder.isWithin('.', r'..\a\b\c'), isFalse);
-      expect(builder.isWithin('.', r'..\..\a\foo\b\c'), isFalse);
-      expect(builder.isWithin(r'C:\', r'C:\baz\bang'), isTrue);
-      expect(builder.isWithin('.', r'C:\baz\bang'), isFalse);
+      var r = new path.Context(style: path.Style.windows, current: r'foo\bar');
+      expect(context.isWithin('.', r'a\b\c'), isTrue);
+      expect(context.isWithin('.', r'..\a\b\c'), isFalse);
+      expect(context.isWithin('.', r'..\..\a\foo\b\c'), isFalse);
+      expect(context.isWithin(r'C:\', r'C:\baz\bang'), isTrue);
+      expect(context.isWithin('.', r'C:\baz\bang'), isFalse);
     });
   });
 
-  group('resolve', () {
+  group('absolute', () {
     test('allows up to seven parts', () {
-      expect(builder.resolve('a'), r'C:\root\path\a');
-      expect(builder.resolve('a', 'b'), r'C:\root\path\a\b');
-      expect(builder.resolve('a', 'b', 'c'), r'C:\root\path\a\b\c');
-      expect(builder.resolve('a', 'b', 'c', 'd'), r'C:\root\path\a\b\c\d');
-      expect(builder.resolve('a', 'b', 'c', 'd', 'e'),
+      expect(context.absolute('a'), r'C:\root\path\a');
+      expect(context.absolute('a', 'b'), r'C:\root\path\a\b');
+      expect(context.absolute('a', 'b', 'c'), r'C:\root\path\a\b\c');
+      expect(context.absolute('a', 'b', 'c', 'd'), r'C:\root\path\a\b\c\d');
+      expect(context.absolute('a', 'b', 'c', 'd', 'e'),
           r'C:\root\path\a\b\c\d\e');
-      expect(builder.resolve('a', 'b', 'c', 'd', 'e', 'f'),
+      expect(context.absolute('a', 'b', 'c', 'd', 'e', 'f'),
           r'C:\root\path\a\b\c\d\e\f');
-      expect(builder.resolve('a', 'b', 'c', 'd', 'e', 'f', 'g'),
+      expect(context.absolute('a', 'b', 'c', 'd', 'e', 'f', 'g'),
           r'C:\root\path\a\b\c\d\e\f\g');
     });
 
     test('does not add separator if a part ends in one', () {
-      expect(builder.resolve(r'a\', 'b', r'c\', 'd'), r'C:\root\path\a\b\c\d');
-      expect(builder.resolve('a/', 'b'), r'C:\root\path\a/b');
+      expect(context.absolute(r'a\', 'b', r'c\', 'd'), r'C:\root\path\a\b\c\d');
+      expect(context.absolute('a/', 'b'), r'C:\root\path\a/b');
     });
 
     test('ignores parts before an absolute path', () {
-      expect(builder.resolve('a', '/b', '/c', 'd'), r'C:\c\d');
-      expect(builder.resolve('a', r'\b', r'\c', 'd'), r'C:\c\d');
-      expect(builder.resolve('a', r'c:\b', 'c', 'd'), r'c:\b\c\d');
-      expect(builder.resolve('a', r'\\b\c', r'\\d\e', 'f'), r'\\d\e\f');
+      expect(context.absolute('a', '/b', '/c', 'd'), r'C:\c\d');
+      expect(context.absolute('a', r'\b', r'\c', 'd'), r'C:\c\d');
+      expect(context.absolute('a', r'c:\b', 'c', 'd'), r'c:\b\c\d');
+      expect(context.absolute('a', r'\\b\c', r'\\d\e', 'f'), r'\\d\e\f');
     });
   });
 
   test('withoutExtension', () {
-    expect(builder.withoutExtension(''), '');
-    expect(builder.withoutExtension('a'), 'a');
-    expect(builder.withoutExtension('.a'), '.a');
-    expect(builder.withoutExtension('a.b'), 'a');
-    expect(builder.withoutExtension(r'a\b.c'), r'a\b');
-    expect(builder.withoutExtension(r'a\b.c.d'), r'a\b.c');
-    expect(builder.withoutExtension(r'a\'), r'a\');
-    expect(builder.withoutExtension(r'a\b\'), r'a\b\');
-    expect(builder.withoutExtension(r'a\.'), r'a\.');
-    expect(builder.withoutExtension(r'a\.b'), r'a\.b');
-    expect(builder.withoutExtension(r'a.b\c'), r'a.b\c');
-    expect(builder.withoutExtension(r'a/b.c/d'), r'a/b.c/d');
-    expect(builder.withoutExtension(r'a\b/c'), r'a\b/c');
-    expect(builder.withoutExtension(r'a\b/c.d'), r'a\b/c');
-    expect(builder.withoutExtension(r'a.b/c'), r'a.b/c');
-    expect(builder.withoutExtension(r'a\b.c\'), r'a\b\');
+    expect(context.withoutExtension(''), '');
+    expect(context.withoutExtension('a'), 'a');
+    expect(context.withoutExtension('.a'), '.a');
+    expect(context.withoutExtension('a.b'), 'a');
+    expect(context.withoutExtension(r'a\b.c'), r'a\b');
+    expect(context.withoutExtension(r'a\b.c.d'), r'a\b.c');
+    expect(context.withoutExtension(r'a\'), r'a\');
+    expect(context.withoutExtension(r'a\b\'), r'a\b\');
+    expect(context.withoutExtension(r'a\.'), r'a\.');
+    expect(context.withoutExtension(r'a\.b'), r'a\.b');
+    expect(context.withoutExtension(r'a.b\c'), r'a.b\c');
+    expect(context.withoutExtension(r'a/b.c/d'), r'a/b.c/d');
+    expect(context.withoutExtension(r'a\b/c'), r'a\b/c');
+    expect(context.withoutExtension(r'a\b/c.d'), r'a\b/c');
+    expect(context.withoutExtension(r'a.b/c'), r'a.b/c');
+    expect(context.withoutExtension(r'a\b.c\'), r'a\b\');
   });
 
   test('fromUri', () {
-    expect(builder.fromUri(Uri.parse('file:///C:/path/to/foo')),
+    expect(context.fromUri(Uri.parse('file:///C:/path/to/foo')),
         r'C:\path\to\foo');
-    expect(builder.fromUri(Uri.parse('file://server/share/path/to/foo')),
+    expect(context.fromUri(Uri.parse('file://server/share/path/to/foo')),
         r'\\server\share\path\to\foo');
-    expect(builder.fromUri(Uri.parse('file:///C:/')), r'C:\');
-    expect(builder.fromUri(Uri.parse('file://server/share')),
+    expect(context.fromUri(Uri.parse('file:///C:/')), r'C:\');
+    expect(context.fromUri(Uri.parse('file://server/share')),
         r'\\server\share');
-    expect(builder.fromUri(Uri.parse('foo/bar')), r'foo\bar');
-    expect(builder.fromUri(Uri.parse('/C:/path/to/foo')), r'C:\path\to\foo');
-    expect(builder.fromUri(Uri.parse('///C:/path/to/foo')), r'C:\path\to\foo');
-    expect(builder.fromUri(Uri.parse('//server/share/path/to/foo')),
+    expect(context.fromUri(Uri.parse('foo/bar')), r'foo\bar');
+    expect(context.fromUri(Uri.parse('/C:/path/to/foo')), r'C:\path\to\foo');
+    expect(context.fromUri(Uri.parse('///C:/path/to/foo')), r'C:\path\to\foo');
+    expect(context.fromUri(Uri.parse('//server/share/path/to/foo')),
         r'\\server\share\path\to\foo');
-    expect(builder.fromUri(Uri.parse('file:///C:/path/to/foo%23bar')),
+    expect(context.fromUri(Uri.parse('file:///C:/path/to/foo%23bar')),
         r'C:\path\to\foo#bar');
-    expect(builder.fromUri(Uri.parse('file://server/share/path/to/foo%23bar')),
+    expect(context.fromUri(Uri.parse('file://server/share/path/to/foo%23bar')),
         r'\\server\share\path\to\foo#bar');
-    expect(builder.fromUri(Uri.parse('_%7B_%7D_%60_%5E_%20_%22_%25_')),
+    expect(context.fromUri(Uri.parse('_%7B_%7D_%60_%5E_%20_%22_%25_')),
         r'_{_}_`_^_ _"_%_');
-    expect(() => builder.fromUri(Uri.parse('http://dartlang.org')),
+    expect(() => context.fromUri(Uri.parse('http://dartlang.org')),
         throwsArgumentError);
   });
 
   test('toUri', () {
-    expect(builder.toUri(r'C:\path\to\foo'),
+    expect(context.toUri(r'C:\path\to\foo'),
         Uri.parse('file:///C:/path/to/foo'));
-    expect(builder.toUri(r'C:\path\to\foo\'),
+    expect(context.toUri(r'C:\path\to\foo\'),
         Uri.parse('file:///C:/path/to/foo/'));
-    expect(builder.toUri(r'C:\'), Uri.parse('file:///C:/'));
-    expect(builder.toUri(r'\\server\share'), Uri.parse('file://server/share'));
-    expect(builder.toUri(r'\\server\share\'),
+    expect(context.toUri(r'C:\'), Uri.parse('file:///C:/'));
+    expect(context.toUri(r'\\server\share'), Uri.parse('file://server/share'));
+    expect(context.toUri(r'\\server\share\'),
         Uri.parse('file://server/share/'));
-    expect(builder.toUri(r'foo\bar'), Uri.parse('foo/bar'));
-    expect(builder.toUri(r'C:\path\to\foo#bar'),
+    expect(context.toUri(r'foo\bar'), Uri.parse('foo/bar'));
+    expect(context.toUri(r'C:\path\to\foo#bar'),
         Uri.parse('file:///C:/path/to/foo%23bar'));
-    expect(builder.toUri(r'\\server\share\path\to\foo#bar'),
+    expect(context.toUri(r'\\server\share\path\to\foo#bar'),
         Uri.parse('file://server/share/path/to/foo%23bar'));
-    expect(builder.toUri(r'C:\_{_}_`_^_ _"_%_'),
+    expect(context.toUri(r'C:\_{_}_`_^_ _"_%_'),
         Uri.parse('file:///C:/_%7B_%7D_%60_%5E_%20_%22_%25_'));
-    expect(builder.toUri(r'_{_}_`_^_ _"_%_'),
+    expect(context.toUri(r'_{_}_`_^_ _"_%_'),
         Uri.parse('_%7B_%7D_%60_%5E_%20_%22_%25_'));
   });
 }