Close stdout and stderr before terminating the VM.

pkg/unittest/lib/vm_config.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.
 
 /**
  * A simple unit test library for running tests on the VM.
  */
 library unittest_vm_config;
 
+import 'dart:async';
 import 'dart:io';
 import 'unittest.dart';
 
 class VMConfiguration extends Configuration {
   // Color constants used for generating messages.
   final String GREEN_COLOR = '\u001b[32m';
   final String RED_COLOR = '\u001b[31m';
   final String MAGENTA_COLOR = '\u001b[35m';
   final String NO_COLOR = '\u001b[0m';
 
@@ skipping 11 matching lines @@
       } else if (testCase.result == FAIL) {
         return "${RED_COLOR}${result}${NO_COLOR}";
       } else if (testCase.result == ERROR) {
         return "${MAGENTA_COLOR}${result}${NO_COLOR}";
       }
     }
     return result;
   }
 
   void onDone(bool success) {
+    int status;
     try {
       super.onDone(success);
-      exit(0);
+      status = 0;
     } catch (ex) {
       // A non-zero exit code is used by the test infrastructure to detect
       // failure.
-      exit(1);
+      status = 1;
     }
+    Future.wait([stdout.close(), stderr.close()]).then((_) {
+      exit(status);
+    });
   }
 }
 
 void useVMConfiguration() {
   unittestConfiguration = _singleton;
 }
 
 final _singleton = new VMConfiguration();