Port dart:io Path tests to package:path.

pkg/path/lib/path.dart

Index: pkg/path/lib/path.dart
diff --git a/pkg/path/lib/path.dart b/pkg/path/lib/path.dart
index b425124cd42e2e86055998bd3fc13004cb66f080..aa7a604a7d701499c24eed94e764a83705db7a08 100644
--- a/pkg/path/lib/path.dart
+++ b/pkg/path/lib/path.dart
@@ -114,6 +114,16 @@ String basenameWithoutExtension(String path) =>
 /// Trailing separators are ignored.
 ///
 ///     builder.dirname('path/to/'); // -> 'path'
+///
+/// If an absolute path contains no directories, only a root, then the root
+/// is returned.
+///
+///     path.dirname('/');  // -> '/' (posix)
+///     path.dirname('c:\');  // -> 'c:\' (windows)
+///
+/// If a relative path has no directories, then '.' is returned.

[Bob Nystrom, 2013/07/15 17:49:29]

Blank line here.

[Bill Hesse, 2013/07/16 12:42:26]

Done.

+///     path.dirname('foo');  // -> '.'
+///     path.dirname('');  // -> '.'
 String dirname(String path) => _builder.dirname(path);
 
 /// Gets the file extension of [path]: the portion of [basename] from the last
@@ -588,8 +598,6 @@ class Builder {
   ///
   ///     builder.normalize('path/./to/..//file.text'); // -> 'path/file.txt'
   String normalize(String path) {
-    if (path == '') return path;
-
     var parsed = _parse(path);
     parsed.normalize();
     return parsed.toString();
@@ -630,8 +638,6 @@ class Builder {
   ///     var builder = new Builder(r'some/relative/path');
   ///     builder.relative(r'/absolute/path'); // -> '/absolute/path'
   String relative(String path, {String from}) {
-    if (path == '') return '.';
-

[Bill Hesse, 2013/07/15 16:58:48]

This is wrong if [from] is not null.  It should work correctly with a null from
as well.

[Bob Nystrom, 2013/07/15 17:49:29]

Eek, you're right.

     from = from == null ? root : this.join(root, from);
 
     // We can't determine the path from a relative path to an absolute path.
@@ -678,8 +684,12 @@ class Builder {
       pathParsed.separators.removeAt(1);
     }
 
-    // If there are any directories left in the root path, we need to walk up
-    // out of them.
+    // If there are any directories left in the from path, we need to walk up
+    // out of them.  If a directory left in the from path is '..', it cannot
+    // be cancelled by adding a '..'.
+    if (fromParsed.parts.length > 0 && fromParsed.parts[0] == '..') {
+      throw new ArgumentError('Unable to find a path to "$path" from "$from".');
+    }

[Bob Nystrom, 2013/07/15 17:49:29]

Can you give me an example where this will come into play? I'd expect that
fromParsed wouldn't have any ".." by the time you get here in most cases. We
should add a test that hits this code path.

If you can get to this case (maybe your builder's root is a relative path with a
leading ".."?), I'd like to see if there's a "right" thing we can do instead of
throwing an exception. People expect path manipulation operations to just work,
so we try very hard not to throw exceptions.

[Bill Hesse, 2013/07/16 12:42:26]

My tests include this case.  Any case with ".." in the from path that is not
matched with one in the to path, when builder.root is '.'.  I think the abstract
case, where you want one relative path relative to another, without regard to
where the paths are based, is important.  I wish it could be done easier than
making a new builder, but I can live with it.  This truly is an exception -
there is no good answer that makes sense for this request, and to rely on the
result for anything would be an error.

     _growListFront(pathParsed.parts, fromParsed.parts.length, '..');
     pathParsed.separators[0] = '';
     pathParsed.separators.insertAll(1,
@@ -688,6 +698,13 @@ class Builder {
     // Corner case: the paths completely collapsed.
     if (pathParsed.parts.length == 0) return '.';
 
+    // Corner case: path was '.' and some '..' directories were added in front.
+    // Don't add a final '/.' in that case.
+    if (pathParsed.parts.length > 1 && pathParsed.parts.last == '.') {
+      pathParsed.parts.removeLast();
+      pathParsed.separators..removeLast()..removeLast()..add('');
+    }

[Bob Nystrom, 2013/07/15 17:49:29]

Nice catch. Add a test for this?

[Bill Hesse, 2013/07/16 12:42:26]

There is a test for this, in my tests.

+
     // Make it relative.
     pathParsed.root = '';
     pathParsed.removeTrailingSeparators();
@@ -1046,7 +1063,8 @@ class _ParsedPath {
     return copy._splitExtension()[0];
   }
 
-  bool get hasTrailingSeparator => !parts.isEmpty && (parts.last == '' || separators.last != '');
+  bool get hasTrailingSeparator =>
+      !parts.isEmpty && (parts.last == '' || separators.last != '');
 
   void removeTrailingSeparators() {
     while (!parts.isEmpty && parts.last == '') {
@@ -1097,7 +1115,7 @@ class _ParsedPath {
     parts = newParts;
     separators = newSeparators;
 
-    // Normalize the Windows root if needed.
+   // Normalize the Windows root if needed.

[Bill Hesse, 2013/07/15 16:58:48]

oops.

     if (root != null && style == Style.windows) {
       root = root.replaceAll('/', '\\');
     }