pkg/unittest: using matcher and mock from packages

pkg/unittest/test/mock_regexp_negative_test.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.
-
-library mock_regexp_negative_test;
-import 'package:unittest/unittest.dart';
-import 'package:unittest/mock.dart';
-
-main() {
-  test('Mocking: RegExp CallMatcher bad', () {
-    var m = new Mock();
-    m.when(callsTo(matches('^[A-Z]'))).
-           alwaysThrow('Method names must start with lower case.');
-    m.Test();
-  });
-}