step 1 in making unittest platform independent.

lib/unittest/unittest_vm.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.
 
 /**
  * A simple unit test library for running tests on the VM.
  */
 #library('unittest');
 
 #import('dart:io');
+#import('dart:isolate');
+
+#source('config.dart');
 #source('shared.dart');
 
-_platformInitialize() {
-  // Do nothing.
-}
-
-_platformDefer(void callback()) {
-  new Timer(0, (timer) {
-    callback();
-  });
-}
-
-_platformStartTests() {
-  // Do nothing.
-}
-
 _platformCompleteTests(int testsPassed, int testsFailed, int testsErrors) {
   // Print each test's result.
   for (final test in _tests) {
     print('${test.result.toUpperCase()}: ${test.description}');
 
     if (test.message != '') {
       print('  ${test.message}');
     }
   }
 
   // Show the summary.
   print('');
 
   var success = false;
   if (testsPassed == 0 && testsFailed == 0 && testsErrors == 0) {
     print('No tests found.');
     // This is considered a failure too: if this happens you probably have a
     // bug in your unit tests.
   } else if (testsFailed == 0 && testsErrors == 0) {
     print('All $testsPassed tests passed.');
     success = true;
   } else {
     print('$testsPassed PASSED, $testsFailed FAILED, $testsErrors ERRORS');
   }
 
   // A non-zero exit code is used by the test infrastructure to detect failure.
   if (!success) exit(1);
 }
+
+Configuration _defaultConfig() {
+  return new Configuration(
+      () {}, // do nothing onInit
+      () {}, // do nothing onStart
+      (testCase) {}, // do nothing onTestResult
+      _platformCompleteTests);
+}