Add toUri and fromUri functions to pathos.

pkg/pathos/test/pathos_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 pathos_posix_test;
 
 import 'package:unittest/unittest.dart';
 import 'package:pathos/path.dart' as path;
 
 main() {
@@ skipping 381 matching lines @@
     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');
     expect(builder.withoutExtension('a/b.c/'), 'a/b/');
     expect(builder.withoutExtension('a/b.c//'), 'a/b//');
   });
+
+  test('fromUri', () {
+    expect(builder.fromUri(Uri.parse('file:///path/to/foo')), '/path/to/foo');
+    expect(builder.fromUri(Uri.parse('file:///')), '/');
+    expect(builder.fromUri(Uri.parse('foo/bar')), 'foo/bar');
+    expect(builder.fromUri(Uri.parse('/path/to/foo')), '/path/to/foo');
+    expect(builder.fromUri(Uri.parse('///path/to/foo')), '/path/to/foo');
+    expect(() => builder.fromUri(Uri.parse('http://dartlang.org')),
+        throwsArgumentError);
+  });
+
+  test('toUri', () {
+    expect(builder.toUri('/path/to/foo'), Uri.parse('file:///path/to/foo'));
+    expect(builder.toUri('/'), Uri.parse('file:///'));
+    expect(builder.toUri('foo/bar'), Uri.parse('foo/bar'));

[Bob Nystrom, 2013/06/13 00:21:18]

This feels odd to me. Will users expect this, or should we convert "foo/bar" to
an absolute path and then return a "file:" URL?

[nweiz, 2013/06/19 00:50:27]

I think this is correct. Think about it from the perspective of manipulating
paths and imported URIs. If you know the relative path from file A to file B and
you want to convert that to an importable URI, you definitely want it to stay
relative during that conversion.

+  });
 }