Make standalone tests not dependent on current working directory.

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 951 matching lines @@
     Expect.equals(bytes.length, 0);
   }
 
   static void testReadAsText() {
     asyncTestStarted();
     var name = getFilename("tests/vm/data/fixed_length_file");
     var f = new File(name);
     f.readAsString(encoding: UTF8).then((text) {
       Expect.isTrue(text.endsWith("42 bytes."));
       Expect.equals(42, text.length);
-      var name = getDataFilename("tests/standalone/io/read_as_text.dat");
+      var name = getFilename("tests/standalone/io/read_as_text.dat");
       var f = new File(name);
       f.readAsString(encoding: UTF8).then((text) {
         Expect.equals(6, text.length);
         var expected = [955, 120, 46, 32, 120, 10];
         Expect.listEquals(expected, text.codeUnits);
         f.readAsString(encoding: LATIN1).then((text) {
           Expect.equals(7, text.length);
           var expected = [206, 187, 120, 46, 32, 120, 10];
           Expect.listEquals(expected, text.codeUnits);
           var readAsStringFuture = f.readAsString(encoding: ASCII);
@@ skipping 16 matching lines @@
       asyncTestDone("testReadAsTextEmptyFile");
       return true;
     });
   }
 
   static void testReadAsTextSync() {
     var name = getFilename("tests/vm/data/fixed_length_file");
     var text = new File(name).readAsStringSync();
     Expect.isTrue(text.endsWith("42 bytes."));
     Expect.equals(42, text.length);
-    name = getDataFilename("tests/standalone/io/read_as_text.dat");
+    name = getFilename("tests/standalone/io/read_as_text.dat");
     text = new File(name).readAsStringSync();
     Expect.equals(6, text.length);
     var expected = [955, 120, 46, 32, 120, 10];
     Expect.listEquals(expected, text.codeUnits);
     // First character is not ASCII. The default ASCII decoder will throw.
     Expect.throws(() => new File(name).readAsStringSync(encoding: ASCII),
                   (e) => e is FileSystemException);
     // We can use an ASCII decoder that inserts the replacement character.
     var lenientAscii = const AsciiCodec(allowInvalid: true);
     text = new File(name).readAsStringSync(encoding: lenientAscii);
@@ skipping 27 matching lines @@
     });
   }
 
   static void testReadAsLinesSync() {
     var name = getFilename("tests/vm/data/fixed_length_file");
     var lines = new File(name).readAsLinesSync();
     Expect.equals(1, lines.length);
     var line = lines[0];
     Expect.isTrue(line.endsWith("42 bytes."));
     Expect.equals(42, line.length);
-    name = getDataFilename("tests/standalone/io/readline_test1.dat");
+    name = getFilename("tests/standalone/io/readline_test1.dat");
     lines = new File(name).readAsLinesSync();
     Expect.equals(10, lines.length);
   }
 
 
   static void testReadAsErrors() {
     asyncTestStarted();
     var f = new File('.');
     Expect.throws(f.readAsBytesSync, (e) => e is FileSystemException);
     Expect.throws(f.readAsStringSync, (e) => e is FileSystemException);
@@ skipping 199 matching lines @@
     if (Platform.operatingSystem != "windows") {
       var brokenLink = new Link(source);
       brokenLink.createSync(dest);
       Expect.throws(() => file.renameSync('xxx'));
       brokenLink.deleteSync();
     }
   }
 
   // Helper method to be able to run the test from the runtime
   // directory, or the top directory.
-  static String getFilename(String path) =>
-      new File(path).existsSync() ? path : 'runtime/$path';
-
-  static String getDataFilename(String path) =>
-      new File(path).existsSync() ? path : '../$path';
+  static String getFilename(String path) {
+    var testPath = Platform.script.resolve('../../../$path');
+    return new File.fromUri(testPath).existsSync()
+        ? testPath.toFilePath()
+        : Platform.script.resolve('../../../runtime/$path').toFilePath();
+  }
 
   // Main test entrypoint.
   static testMain() {
     asyncStart();
 
     testRead();
     testReadSync();
     testReadStream();
     testLengthSync();
     testPositionSync();
@@ skipping 44 matching lines @@
       testLastModified();
       testDoubleAsyncOperation();
       asyncEnd();
     });
   }
 }
 
 main() {
   FileTest.testMain();
 }