Fix argument processing for RandomAccessFile.writeFrom

tests/standalone/io/file_test.dart

 // Copyright (c) 2013, 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 file I/O.
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:collection';
 import 'dart:io';
@@ skipping 698 matching lines @@
     RandomAccessFile openedFile = file.openSync(mode: WRITE);
     openedFile.writeFromSync(buffer, 0, 10);
     Expect.equals(10, openedFile.lengthSync());
     openedFile.truncateSync(5);
     Expect.equals(5, openedFile.lengthSync());
     openedFile.closeSync();
     file.deleteSync();
     Expect.isFalse(file.existsSync());
   }
 
+  static void testWriteFrom() async {
+    asyncTestStarted();
+    File file = new File(tempDirectory.path + "/out_write_from");
+
+    var buffer = const [1, 2, 3];
+    var openedFile = await file.open(mode: WRITE);
+
+    await openedFile.writeFrom(buffer);
+    var result = []..addAll(buffer);;
+
+    write([start, end]) async {
+      await openedFile.writeFrom(buffer, start, end);
+      result.addAll(buffer.sublist(start, end));
+    }
+    await write(0, 3);
+    await write(0, 2);
+    await write(1, 2);
+    await write(1, 3);
+    await write(2, 3);
+
+    var bytesFromFile = await file.readAsBytes();
+    Expect.listEquals(result, bytesFromFile);
+    asyncTestDone("testWriteFrom");
+  }
+
+  static void testWriteFromSync() {
+    File file = new File(tempDirectory.path + "/out_write_from_sync");
+
+    var buffer = const [1, 2, 3];
+    var openedFile = file.openSync(mode: WRITE);
+
+    openedFile.writeFromSync(buffer);
+    var result = []..addAll(buffer);;
+
+    write([start, end]) {
+      openedFile.writeFromSync(buffer, start, end);
+      result.addAll(buffer.sublist(start, end));
+    }
+    write(0, 3);
+    write(0, 2);
+    write(1, 2);
+    write(1, 3);
+    write(2, 3);
+
+    var bytesFromFile = file.readAsBytesSync();
+    Expect.listEquals(result, bytesFromFile);
+  }
+
   // Tests exception handling after file was closed.
   static void testCloseException() {
     bool exceptionCaught = false;
     bool wrongExceptionCaught = false;
     File input = new File(tempDirectory.path + "/out_close_exception");
     RandomAccessFile openedFile = input.openSync(mode: WRITE);
     openedFile.closeSync();
     try {
       openedFile.readByteSync();
     } on FileSystemException catch (ex) {
@@ skipping 591 matching lines @@
       testReadWriteStreamLargeFile();
       testReadAsBytes();
       testReadAsBytesEmptyFile();
       testReadAsText();
       testReadAsTextEmptyFile();
       testReadAsLines();
       testReadAsErrors();
       testPosition();
       testTruncate();
       testTruncateSync();
+      testWriteFrom();
+      testWriteFromSync();
       testCloseException();
       testCloseExceptionStream();
       testBufferOutOfBoundsException();
       testAppend();
       testAppendSync();
       testWriteAppend();
       testOutputStreamWriteAppend();
       testOutputStreamWriteString();
       testWriteVariousLists();
       testDirectory();
       testDirectorySync();
       testWriteStringUtf8();
       testWriteStringUtf8Sync();
       testRename(targetExists: false);
       testRenameSync(targetExists: false);
       testRename(targetExists: true);
       testRenameSync(targetExists: true);
       testLastModified();
       testDoubleAsyncOperation();
       asyncEnd();
     });
   }
 }
 
 main() {
   FileTest.testMain();
 }