Support length operation without opening file.

tests/standalone/src/io/FileErrorTest.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.
 //
 // Dart test program for testing error handling in file I/O.
 
 #import("dart:io");
 #import("dart:isolate");
 
 Directory tempDir() {
   var d = new Directory('');
   d.createTempSync();
   return d;
 }
 
 
-bool checkOpenNonExistentFileException(e) {
+bool checkNonExistentFileException(e, str) {
   Expect.isTrue(e is FileIOException);
   Expect.isTrue(e.osError != null);
-  Expect.isTrue(e.toString().indexOf("Cannot open file") != -1);
+  Expect.isTrue(e.toString().indexOf(str) != -1);
   Platform platform = new Platform();
   if (platform.operatingSystem() == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
   } else if (platform.operatingSystem() == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
   } else if (platform.operatingSystem() == "windows") {
     Expect.isTrue(
         e.toString().indexOf(
             "The system cannot find the file specified") != -1);
   }
   // File not not found has error code 2 on all supported platforms.
   Expect.equals(2, e.osError.errorCode);
 
   return true;
 }
 
+
+bool checkOpenNonExistentFileException(e) {
+  return checkNonExistentFileException(e, "Cannot open file");
+}
+
+
+bool checkDeleteNonExistentFileException(e) {
+  return checkNonExistentFileException(e, "Cannot delete file");
+}
+
+
+bool checkLengthNonExistentFileException(e) {
+  return checkNonExistentFileException(e, "Cannot retrieve length of file");
+}
+
+
 void testOpenNonExistent() {
   Directory temp = tempDir();
   ReceivePort p = new ReceivePort();
   p.receive((x, y) {
     p.close();
     temp.deleteRecursivelySync();
   });
   var file = new File("${temp.path}/nonExistentFile");
 
   // Non-existing file should throw exception.
   Expect.throws(() => file.openSync(),
                 (e) => checkOpenNonExistentFileException(e));
 
   file.open(FileMode.READ, (raf) => Expect.fail("Unreachable code"));
   file.onError = (e) {
     checkOpenNonExistentFileException(e);
     p.toSendPort().send(null);
   };
 }
 
-bool checkDeleteNonExistentFileException(e) {
-  Expect.isTrue(e is FileIOException);
-  Expect.isTrue(e.osError != null);
-  Expect.isTrue(e.toString().indexOf("Cannot delete file") != -1);
-  Platform platform = new Platform();
-  if (platform.operatingSystem() == "linux") {
-    Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (platform.operatingSystem() == "macos") {
-    Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
-  } else if (platform.operatingSystem() == "windows") {
-    Expect.isTrue(
-        e.toString().indexOf(
-            "The system cannot find the file specified") != -1);
-  }
-  // File not not found has error code 2 on all supported platforms.
-  Expect.equals(2, e.osError.errorCode);
-
-  return true;
-}
 
 void testDeleteNonExistent() {
   Directory temp = tempDir();
   ReceivePort p = new ReceivePort();
   p.receive((x, y) {
     p.close();
     temp.deleteRecursivelySync();
   });
   var file = new File("${temp.path}/nonExistentFile");
 
   // Non-existing file should throw exception.
   Expect.throws(() => file.deleteSync(),
                 (e) => checkDeleteNonExistentFileException(e));
 
   file.delete(() => Expect.fail("Unreachable code"));
   file.onError = (e) {
     checkDeleteNonExistentFileException(e);
     p.toSendPort().send(null);
   };
 }
 
+
+void testLengthNonExistent() {
+  Directory temp = tempDir();
+  ReceivePort p = new ReceivePort();
+  p.receive((x, y) {
+    p.close();
+    temp.deleteRecursivelySync();
+  });
+  var file = new File("${temp.path}/nonExistentFile");
+
+  // Non-existing file should throw exception.
+  Expect.throws(() => file.lengthSync(),
+                (e) => checkLengthNonExistentFileException(e));
+
+  file.length((len) => Expect.fail("Unreachable code"));
+  file.onError = (e) {
+    checkLengthNonExistentFileException(e);
+    p.toSendPort().send(null);
+  };
+}
+
+
 bool checkCreateInNonExistentDirectoryException(e) {
   Expect.isTrue(e is FileIOException);
   Expect.isTrue(e.osError != null);
   Expect.isTrue(e.toString().indexOf("Cannot create file") != -1);
   Platform platform = new Platform();
   if (platform.operatingSystem() == "linux") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
     Expect.equals(2, e.osError.errorCode);
   } else if (platform.operatingSystem() == "macos") {
     Expect.isTrue(e.toString().indexOf("No such file or directory") != -1);
@@ skipping 318 matching lines @@
     checkFileClosedException(e);
     if (--errorCount == 0) {
       p.toSendPort().send(null);
     }
   };
 }
 
 main() {
   testOpenNonExistent();
   testDeleteNonExistent();
+  testLengthNonExistent();
   testCreateInNonExistentDirectory();
   testFullPathOnNonExistentDirectory();
   testDirectoryInNonExistentDirectory();
   testReadAsBytesNonExistent();
   testReadAsTextNonExistent();
   testReadAsLinesNonExistent();
   testWriteByteToReadOnlyFile();
   testWriteListToReadOnlyFile();
   testTruncateReadOnlyFile();
   testOperateOnClosedFile();
 }