Handle relative paths where the trailing directory has an extension.

utils/tests/pub/path/path_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;
 
 import 'dart:io' as io;
 
 import '../../../../pkg/unittest/lib/unittest.dart';
 import '../../../pub/path.dart' as path;
@@ skipping 236 matching lines @@
         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('given absolute with differnt root prefix', () {
+    test('from a root with extension', () {
+      var r = new path.Builder(style: path.Style.windows, root: r'C:\dir.ext');
+      expect(r.relative(r'C:\dir.ext\file'), 'file');
+    });
+
+    test('given absolute with different root prefix', () {
       expect(builder.relative(r'D:\a\b'), r'D:\a\b');
       expect(builder.relative(r'\\a\b'), r'\\a\b');
     });
   });
 
   group('resolve', () {
     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');
@@ skipping 26 matching lines @@
     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');
   });
 }