Add support for setUpAll and tearDownAll.

lib/test.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.
 
 library test;
 
 import 'dart:async';
 
 import 'package:path/path.dart' as p;
 
@@ skipping 169 matching lines @@
 /// asynchronous; if so, it must return a [Future].
 ///
 /// If this is called within a test group, it applies only to tests in that
 /// group. [callback] will be run before any tear-down callbacks in parent
 /// groups or at the top level.
 ///
 /// Each callback at the top level or in a given group will be run in the
 /// reverse of the order they were declared.
 void tearDown(callback()) => _declarer.tearDown(callback);
 
+/// Registers a function to be run once before all tests.
+///
+/// [callback] may be asynchronous; if so, it must return a [Future].
+///
+/// If this is called within a test group, [callback] will run before all tests
+/// in that group. It will be run after any [setUpAll] callbacks in parent
+/// groups or at the top level. It won't be run if none of the tests in the
+/// group are run.
+///
+/// **Note**: This function makes it very easy to accidentally introduce hidden
+/// dependencies between tests that should be isolated. In general, you should
+/// prefer [setUp], and only use [setUpAll] if the callback is prohibitively
+/// slow.
+void setUpAll(callback()) => _declarer.setUpAll(callback);
+
+/// Registers a function to be run once after all tests.
+///
+/// If this is called within a test group, [callback] will run after all tests
+/// in that group. It will be run before any [tearDownAll] callbacks in parent
+/// groups or at the top level. It won't be run if none of the tests in the
+/// group are run.
+///
+/// **Note**: This function makes it very easy to accidentally introduce hidden
+/// dependencies between tests that should be isolated. In general, you should
+/// prefer [tearDown], and only use [tearDOwnAll] if the callback is
+/// prohibitively slow.
+void tearDownAll(callback()) => _declarer.tearDownAll(callback);
+
 /// Registers an exception that was caught for the current test.
 void registerException(error, [StackTrace stackTrace]) {
   // This will usually forward directly to [Invoker.current.handleError], but
   // going through the zone API allows other zones to consistently see errors.
   Zone.current.handleUncaughtError(error, stackTrace);
 }