Run test tearDowns and clean up temporary directories when a signal is caught.

test/runner/parse_metadata_test.dart

 // Copyright (c) 2015, 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.
 
 @TestOn("vm")
 
 import 'dart:io';
 
 import 'package:path/path.dart' as p;
 import 'package:test/test.dart';
 import 'package:test/src/backend/platform_selector.dart';
 import 'package:test/src/backend/test_platform.dart';
 import 'package:test/src/runner/parse_metadata.dart';
+import 'package:test/src/util/io.dart';
 
 String _sandbox;
 String _path;
 
 void main() {
   setUp(() {
-    _sandbox = Directory.systemTemp.createTempSync('test_').path;
+    _sandbox = createTempDir();
     _path = p.join(_sandbox, "test.dart");
   });
 
   tearDown(() {
     new Directory(_sandbox).deleteSync(recursive: true);
   });
 
   test("returns empty metadata for an empty file", () {
     new File(_path).writeAsStringSync("");
     var metadata = parseMetadata(_path);
@@ skipping 60 matching lines @@
       expect(() => parseMetadata(_path), throwsFormatException);
     });
 
     test("multiple @TestOns", () {
       new File(_path).writeAsStringSync(
           "@TestOn('foo')\n@TestOn('bar')\nlibrary foo;");
       expect(() => parseMetadata(_path), throwsFormatException);
     });
   });
 }