Handle relative paths where the trailing directory has an extension.

utils/tests/pub/path/path_posix_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 215 matching lines @@
         // normalizes.
         expect(r.relative(''), '.');
         expect(r.relative('.'), '.');
         expect(r.relative('..'), '..');
         expect(r.relative('a'), 'a');
         expect(r.relative('a/b.txt'), 'a/b.txt');
         expect(r.relative('../a/b.txt'), '../a/b.txt');
         expect(r.relative('a/./b/../c.txt'), 'a/c.txt');
       });
     });
+
+    test('from a root with extension', () {
+      var r = new path.Builder(style: path.Style.posix, root: '/dir.ext');
+      expect(r.relative('/dir.ext/file'), 'file');
+    });
   });
 
   group('resolve', () {
     test('allows up to seven parts', () {
       expect(builder.resolve('a'), '/root/path/a');
       expect(builder.resolve('a', 'b'), '/root/path/a/b');
       expect(builder.resolve('a', 'b', 'c'), '/root/path/a/b/c');
       expect(builder.resolve('a', 'b', 'c', 'd'), '/root/path/a/b/c/d');
       expect(builder.resolve('a', 'b', 'c', 'd', 'e'), '/root/path/a/b/c/d/e');
       expect(builder.resolve('a', 'b', 'c', 'd', 'e', 'f'),
@@ skipping 24 matching lines @@
     expect(builder.withoutExtension('a/'), 'a/');
     expect(builder.withoutExtension('a/b/'), 'a/b/');
     expect(builder.withoutExtension('a/.'), 'a/.');
     expect(builder.withoutExtension('a/.b'), 'a/.b');
     expect(builder.withoutExtension('a.b/c'), 'a.b/c');
     expect(builder.withoutExtension(r'a.b\c'), r'a');
     expect(builder.withoutExtension(r'a/b\c'), r'a/b\c');
     expect(builder.withoutExtension(r'a/b\c.d'), r'a/b\c');
   });
 }