Implement tests for Directory (flutter#19)

Author: tvolkert

lib/src/backends/memory/memory_directory.dart

@@ -30,6 +30,7 @@ class _MemoryDirectory extends _MemoryFileSystemEntity implements Directory {
         }
         return null;
       },
+      resolveTailLink: true,
     );
     if (node.type != expectedType) {
       // There was an existing non-directory node at this object's path
@@ -42,8 +43,8 @@ class _MemoryDirectory extends _MemoryFileSystemEntity implements Directory {
 
   @override
   Directory createTempSync([String prefix]) {
-    prefix ??= '';
-    String fullPath = '$path$_separator$prefix';
+    prefix = (prefix ?? '') + 'rand';
+    String fullPath = fileSystem._context.join(path, prefix);
     String dirname = fileSystem._context.dirname(fullPath);
     String basename = fileSystem._context.basename(fullPath);
     _DirectoryNode node = fileSystem._findNode(dirname);
@@ -55,7 +56,8 @@ class _MemoryDirectory extends _MemoryFileSystemEntity implements Directory {
     }
     _DirectoryNode tempDir = new _DirectoryNode(node);
     node.children[name()] = tempDir;
-    return new _MemoryDirectory(fileSystem, '$dirname$_separator${name()}');
+    return new _MemoryDirectory(
+        fileSystem, fileSystem._context.join(dirname, name()));
   }
 
   @override
@@ -95,24 +97,28 @@ class _MemoryDirectory extends _MemoryFileSystemEntity implements Directory {
   }) {
     _DirectoryNode node = backing;
     List<FileSystemEntity> listing = <FileSystemEntity>[];
-    Set<_LinkNode> visitedLinks = new Set<_LinkNode>();
     List<_PendingListTask> tasks = <_PendingListTask>[
       new _PendingListTask(
         node,
         path.endsWith(_separator) ? path.substring(0, path.length - 1) : path,
+        new Set<_LinkNode>(),
       ),
     ];
     while (tasks.isNotEmpty) {
       _PendingListTask task = tasks.removeLast();
       task.dir.children.forEach((String name, _Node child) {
-        String childPath = '${task.path}$_separator$name';
-        if (followLinks && _isLink(child) && visitedLinks.add(child)) {
-          child = (child as _LinkNode).referent;
+        Set<_LinkNode> breadcrumbs = new Set<_LinkNode>.from(task.breadcrumbs);
+        String childPath = fileSystem._context.join(task.path, name);
+        while (followLinks && _isLink(child) && breadcrumbs.add(child)) {
+          _Node referent = (child as _LinkNode).referentOrNull;
+          if (referent != null) {
+            child = referent;
+          }
         }
         if (_isDirectory(child)) {
           listing.add(new _MemoryDirectory(fileSystem, childPath));
           if (recursive) {
-            tasks.add(new _PendingListTask(child, childPath));
+            tasks.add(new _PendingListTask(child, childPath, breadcrumbs));
           }
         } else if (_isLink(child)) {
           listing.add(new _MemoryLink(fileSystem, childPath));
@@ -131,5 +137,6 @@ class _MemoryDirectory extends _MemoryFileSystemEntity implements Directory {
 class _PendingListTask {
   final _DirectoryNode dir;
   final String path;
-  _PendingListTask(this.dir, this.path);
+  final Set<_LinkNode> breadcrumbs;
+  _PendingListTask(this.dir, this.path, this.breadcrumbs);
 }

lib/src/backends/memory/memory_file_system.dart

@@ -209,19 +209,20 @@ class MemoryFileSystem extends FileSystem {
       if (i < finalSegment) {
         _PathGenerator subpath = _subpath(parts, 0, i);
         _checkExists(child, subpath);
+        if (pathWithSymlinks != null) {
+          pathWithSymlinks.add(basename);
+        }
         if (_isLink(child)) {
           child = _resolveLinks(child, subpath, ledger: pathWithSymlinks);
-        } else if (pathWithSymlinks != null) {
-          pathWithSymlinks..add(_separator)..add(basename);
         }
         _checkIsDir(child, subpath);
         directory = child;
       } else if (pathWithSymlinks != null) {
-        pathWithSymlinks..add(_separator)..add(basename);
+        pathWithSymlinks.add(basename);
       }
     }
     if (_isLink(child) && resolveTailLink) {
-      child = _resolveLinks(child, () => path);
+      child = _resolveLinks(child, () => path, ledger: pathWithSymlinks);
     }
     return child;
   }

lib/src/backends/memory/memory_file_system_entity.dart

@@ -63,8 +63,8 @@ abstract class _MemoryFileSystemEntity implements FileSystemEntity {
         pathWithSymlinks: ledger, resolveTailLink: true);
     _checkExists(node, () => path);
     String resolved = ledger.join(_separator);
-    if (!isAbsolute) {
-      resolved = fileSystem._cwd + resolved;
+    if (!_isAbsolute(resolved)) {
+      resolved = fileSystem._cwd + _separator + resolved;
     }
     return fileSystem._context.normalize(resolved);
   }
@@ -88,7 +88,7 @@ abstract class _MemoryFileSystemEntity implements FileSystemEntity {
       if (node is _DirectoryNode && node.children.isNotEmpty) {
         throw new io.FileSystemException('Directory not empty', path);
       }
-      if (node.type != expectedType) {
+      if (node.stat.type != expectedType) {
         throw new io.FileSystemException(
             'Not a ${expectedType.toString().toLowerCase()}', path);
       }
@@ -113,7 +113,7 @@ abstract class _MemoryFileSystemEntity implements FileSystemEntity {
   FileSystemEntity get absolute {
     String absolutePath = path;
     if (!_isAbsolute(absolutePath)) {
-      absolutePath = '${fileSystem._cwd}$_separator$absolutePath';
+      absolutePath = fileSystem._context.join(fileSystem._cwd, absolutePath);
     }
     return _clone(absolutePath);
   }
@@ -136,11 +136,16 @@ abstract class _MemoryFileSystemEntity implements FileSystemEntity {
   /// If an entity already existed at this path, [createChild] will not be
   /// invoked at all, and this method will return with the backing node for the
   /// existing entity (whose type may differ from this entity's type).
+  ///
+  /// If [resolveTailLink] is true and the result node is a link, this will
+  /// resolve it to its target prior to returning it.
   _Node _createSync(
-    _Node createChild(_DirectoryNode parent, bool isFinalSegment),
-  ) {
+    _Node createChild(_DirectoryNode parent, bool isFinalSegment), {
+    bool resolveTailLink: false,
+  }) {
     return fileSystem._findNode(
       path,
+      resolveTailLink: resolveTailLink,
       segmentVisitor: (
         _DirectoryNode parent,
         String childName,
@@ -183,6 +188,9 @@ abstract class _MemoryFileSystemEntity implements FileSystemEntity {
     _RenameOverwriteValidator<dynamic> validateOverwriteExistingEntity,
   }) {
     _Node node = backing;
+    if (node.stat.type != expectedType) {
+      throw new io.FileSystemException('No such file or directory', path);
+    }
     fileSystem._findNode(
       newPath,
       segmentVisitor: (

lib/src/backends/memory/node.dart

@@ -150,9 +150,24 @@ class _LinkNode extends _Node {
     assert(target != null && target.isNotEmpty);
   }
 
+  /// Gets the node backing for this link's target. Throws a
+  /// [io.FileSystemException] if this link references a non-existent file
+  /// system entity.
+  _Node get referent {
+    _Node node = fs._findNode(target, reference: this);
+    _checkExists(node, () => target);
+    return node;
+  }
+
   /// Gets the node backing for this link's target, or null if this link
   /// references a non-existent file system entity.
-  _Node get referent => fs._findNode(target, reference: this);
+  _Node get referentOrNull {
+    try {
+      return referent;
+    } on io.FileSystemException {
+      return null;
+    }
+  }
 
   @override
   io.FileSystemEntityType get type => io.FileSystemEntityType.LINK;
@@ -164,7 +179,7 @@ class _LinkNode extends _Node {
     }
     reentrant = true;
     try {
-      _Node node = referent;
+      _Node node = referentOrNull;
       return node == null ? _MemoryFileStat._notFound : node.stat;
     } finally {
       reentrant = false;

lib/src/backends/memory/utils.dart

@@ -62,7 +62,8 @@ _Node _resolveLinks(
   while (_isLink(node)) {
     link = node;
     if (!breadcrumbs.add(node)) {
-      throw new io.FileSystemException('Loop found in link chain', path());
+      throw new io.FileSystemException(
+          'Too many levels of symbolic links', path());
     }
     if (ledger != null) {
       if (_isAbsolute(link.target)) {