Better handling of reading empty files

tests/standalone/io/file_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.
 //
 // Dart test program for testing file I/O.
 
 #import("dart:io");
 #import("dart:isolate");
 
 class MyListOfOneElement implements List {
@@ skipping 985 matching lines @@
       Expect.equals(42, result);
     });
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
     f.readAsBytes().then((bytes) {
       Expect.isTrue(new String.fromCharCodes(bytes).endsWith("42 bytes."));
       port.toSendPort().send(bytes.length);
     });
   }
 
+  static void testReadAsBytesEmptyFile() {
+    var port = new ReceivePort();
+    port.receive((result, replyTo) {
+      port.close();
+      Expect.equals(0, result);
+    });
+    var name = getFilename("tests/vm/data/empty_file");
+    var f = new File(name);
+    f.readAsBytes().then((bytes) {
+      port.toSendPort().send(bytes.length);
+    });
+  }
+
   static void testReadAsBytesSync() {
     var name = getFilename("tests/vm/data/fixed_length_file");
     var bytes = new File(name).readAsBytesSync();
     Expect.isTrue(new String.fromCharCodes(bytes).endsWith("42 bytes."));
     Expect.equals(bytes.length, 42);
   }
 
+  static void testReadAsBytesSyncEmptyFile() {
+    var name = getFilename("tests/vm/data/empty_file");
+    var bytes = new File(name).readAsBytesSync();
+    Expect.equals(bytes.length, 0);
+  }
+
   static void testReadAsText() {
     var port = new ReceivePort();
     port.receive((result, replyTo) {
       port.close();
       Expect.equals(1, result);
     });
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
     f.readAsText(Encoding.UTF_8).then((text) {
       Expect.isTrue(text.endsWith("42 bytes."));
@@ skipping 14 matching lines @@
           });
           readAsTextFuture.handleException((e) {
             port.toSendPort().send(1);
             return true;
           });
         });
       });
     });
   }
 
+  static void testReadAsTextEmptyFile() {
+    var port = new ReceivePort();
+    port.receive((result, replyTo) {
+      port.close();
+      Expect.equals(0, result);
+    });
+    var name = getFilename("tests/vm/data/empty_file");
+    var f = new File(name);
+    f.readAsText(Encoding.UTF_8).then((text) {
+      port.toSendPort().send(text.length);
+      return true;
+    });
+  }
+
   static void testReadAsTextSync() {
     var name = getFilename("tests/vm/data/fixed_length_file");
     var text = new File(name).readAsTextSync();
     Expect.isTrue(text.endsWith("42 bytes."));
     Expect.equals(42, text.length);
     name = getDataFilename("tests/standalone/io/read_as_text.dat");
     text = new File(name).readAsTextSync();
     Expect.equals(6, text.length);
     var expected = [955, 120, 46, 32, 120, 10];
     Expect.listEquals(expected, text.charCodes());
     Expect.throws(() { new File(name).readAsTextSync(Encoding.ASCII); });
     text = new File(name).readAsTextSync(Encoding.ISO_8859_1);
     expected = [206, 187, 120, 46, 32, 120, 10];
     Expect.equals(7, text.length);
     Expect.listEquals(expected, text.charCodes());
   }
 
+  static void testReadAsTextSyncEmptyFile() {
+    var name = getFilename("tests/vm/data/empty_file");
+    var text = new File(name).readAsTextSync();
+    Expect.equals(0, text.length);
+  }
+
   static void testReadAsLines() {
     var port = new ReceivePort();
     port.receive((result, replyTo) {
       port.close();
       Expect.equals(42, result);
     });
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
     f.readAsLines(Encoding.UTF_8).then((lines) {
       Expect.equals(1, lines.length);
@@ skipping 120 matching lines @@
     testReadSync();
     testReadStream();
     testLength();
     testLengthSync();
     testPosition();
     testPositionSync();
     testOpenDirectoryAsFile();
     testOpenDirectoryAsFileSync();
     testOpenFileFromPath();
     testReadAsBytes();
+    testReadAsBytesEmptyFile();
     testReadAsBytesSync();
+    testReadAsBytesSyncEmptyFile();
     testReadAsText();
+    testReadAsTextEmptyFile();
     testReadAsTextSync();
+    testReadAsTextSyncEmptyFile();
     testReadAsLines();
     testReadAsLinesSync();
     testReadAsErrors();
     testLastModified();
     testLastModifiedSync();
 
     createTempDirectory(() {
       testReadWrite();
       testReadWriteSync();
       testReadWriteStream();
@@ skipping 13 matching lines @@
       testWriteVariousLists();
       testDirectory();
       testDirectorySync();
     });
   }
 }
 
 main() {
   FileTest.testMain();
 }