More String + elimination in tests

tests/standalone/io/stream_pipe_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.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 #import("dart:io");
 #import("dart:isolate");
 #source("testing_server.dart");
 
 // Helper method to be able to run the test from the runtime
 // directory, or the top directory.
 String getDataFilename(String path) =>
-    new File(path).existsSync() ? path : '../' + path;
+    new File(path).existsSync() ? path : '../$path';
 
 
 bool compareFileContent(String fileName1,
                         String fileName2,
                         [int file1Offset = 0,
                          int file2Offset = 0,
                          int count]) {
   var file1 = new File(fileName1).openSync();
   var file2 = new File(fileName2).openSync();
   var length1 = file1.lengthSync();
@@ skipping 51 matching lines @@
     void connectHandler() {
       String srcFileName =
           getDataFilename("tests/standalone/io/readline_test1.dat");
 
       SocketOutputStream socketOutput = _socket.outputStream;
       InputStream fileInput = new File(srcFileName).openInputStream();
 
       fileInput.onClosed = () {
         SocketInputStream socketInput = _socket.inputStream;
         var tempDir = new Directory('').createTempSync();
-        var dstFileName = tempDir.path + "/readline_test1.dat";
+        var dstFileName = tempDir.path.concat("/readline_test1.dat");
         var dstFile = new File(dstFileName);
         dstFile.createSync();
         var fileOutput = dstFile.openOutputStream();
 
         socketInput.onClosed = () {
           // Check that the resulting file is equal to the initial
           // file.
           fileOutput.onClosed = () {
             bool result = compareFileContent(srcFileName, dstFileName);
             new File(dstFileName).deleteSync();
@@ skipping 63 matching lines @@
   // Force test to timeout if one of the handlers is
   // not called.
   ReceivePort donePort = new ReceivePort();
   donePort.receive((message, ignore) { donePort.close(); });
 
   String srcFileName =
       getDataFilename("tests/standalone/io/readline_test1.dat");
   var srcStream = new File(srcFileName).openInputStream();
 
   var tempDir = new Directory('').createTempSync();
-  String dstFileName = tempDir.path + "/readline_test1.dat";
+  String dstFileName = tempDir.path.concat("/readline_test1.dat");
   new File(dstFileName).createSync();
   var dstStream = new File(dstFileName).openOutputStream();
 
   dstStream.onClosed = () {
     bool result = compareFileContent(srcFileName, dstFileName);
     new File(dstFileName).deleteSync();
     tempDir.deleteSync();
     Expect.isTrue(result);
     donePort.toSendPort().send(null);
   };
 
   srcStream.pipe(dstStream);
 }
 
 
 // Test piping from one file to another and write additional data to
 // the output stream after piping finished.
 testFileToFilePipe2() {
   // Force test to timeout if one of the handlers is
   // not called.
   ReceivePort donePort = new ReceivePort();
   donePort.receive((message, ignore) { donePort.close(); });
 
   String srcFileName =
       getDataFilename("tests/standalone/io/readline_test1.dat");
   var srcFile = new File(srcFileName);
   var srcStream = srcFile.openInputStream();
 
   var tempDir = new Directory('').createTempSync();
-  var dstFileName = tempDir.path + "/readline_test1.dat";
+  var dstFileName = tempDir.path.concat("/readline_test1.dat");
   var dstFile = new File(dstFileName);
   dstFile.createSync();
   var dstStream = dstFile.openOutputStream();
 
   srcStream.onClosed = () {
     dstStream.write([32]);
     dstStream.close();
     dstStream.onClosed = () {
       var src = srcFile.openSync();
       var dst = dstFile.openSync();
@@ skipping 25 matching lines @@
   // not called.
   ReceivePort donePort = new ReceivePort();
   donePort.receive((message, ignore) { donePort.close(); });
 
   String srcFileName =
       getDataFilename("tests/standalone/io/readline_test1.dat");
   var srcFile = new File(srcFileName);
   var srcStream = srcFile.openInputStream();
 
   var tempDir = new Directory('').createTempSync();
-  var dstFileName = tempDir.path + "/readline_test1.dat";
+  var dstFileName = tempDir.path.concat("/readline_test1.dat");
   var dstFile = new File(dstFileName);
   dstFile.createSync();
   var dstStream = dstFile.openOutputStream();
 
   srcStream.onClosed = () {
     var srcStream2 = srcFile.openInputStream();
 
     dstStream.onClosed = () {
       var src = srcFile.openSync();
       var dst = dstFile.openSync();
@@ skipping 21 matching lines @@
   srcStream.pipe(dstStream, close: false);
 }
 
 
 main() {
   testFileToFilePipe1();
   testFileToFilePipe2();
   testFileToFilePipe3();
   PipeServerGame echoServerGame = new PipeServerGame.start();
 }