step 1 in making unittest platform independent.

lib/unittest/config.dart

+// Copyright (c) 2011, 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.
+
+/** Hooks to configure the unittest library for different platforms. */
+interface Configuration default _DefaultConfiguration {
+  /**
+   * Called as soon as the unittest framework becomes initialized. This is done
+   * even before tests are added to the test framework. It might be used to
+   * determine/debug errors that occur before the test harness starts executing.
+   */
+  void onInit();
+
+  /**
+   * Called as soon as the unittest framework starts running. Used commonly to
+   * tell the vm or browser that tests are still running and the process should
+   * wait until they are done.
+   */
+  void onStart();
+
+  /**
+   * Called when each test is completed. The default implementation throws an
+   * exception if the test failed. Other implementations might choose to ignore
+   * this callback and present a summary result in [onDone].
+   */
+  void onTestResult(TestCase testCase);
+
+  /**
+   * Called with the result of all test cases. The default implementation prints
+   * the result summary using the built-in [print] command. Browser tests
+   * commonly override this to reformat the output.
+   */
+  void onDone(int passed, int failed, int errors, List<TestCase> results);
+}
+
+// TODO(sigmund): make this the default config.
+//class _DefaultConfiguration() {
+//  void onInit() {}
+//  void onStart() {}
+//  void onResult(TestCase testCase) { 
+//    if (testCase.result != _PASS) {
+//      Expect.fail("FAIL: ${testCase.description}");
+//    }
+// }
+// void onDone(int passed, int failed, int errors, List<TestCase> results) {
+//    if (failed == 0 && errors == 0) {
+//      print("PASS");
+//    }
+//  }
+//}