1// Copyright (c) 2011 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_TEST_TEST_REG_UTIL_H_
6#define BASE_TEST_TEST_REG_UTIL_H_
7
8// Registry utility functions used only by tests.
9
10#include "base/basictypes.h"
11#include "base/memory/scoped_vector.h"
12#include "base/strings/string16.h"
13#include "base/time/time.h"
14#include "base/win/registry.h"
15
16namespace registry_util {
17
18// Allows a test to easily override registry hives so that it can start from a
19// known good state, or make sure to not leave any side effects once the test
20// completes. This supports parallel tests. All the overrides are scoped to the
21// lifetime of the override manager. Destroy the manager to undo the overrides.
22//
23// Overridden hives use keys stored at, for instance:
24//   HKCU\Software\Chromium\TempTestKeys\
25//       13028145911617809$02AB211C-CF73-478D-8D91-618E11998AED
26// The key path are comprises of:
27//   - The test key root, HKCU\Software\Chromium\TempTestKeys\
28//   - The base::Time::ToInternalValue of the creation time. This is used to
29//     delete stale keys left over from crashed tests.
30//   - A GUID used for preventing name collisions (although unlikely) between
31//     two RegistryOverrideManagers created with the same timestamp.
32class RegistryOverrideManager {
33 public:
34  RegistryOverrideManager();
35  ~RegistryOverrideManager();
36
37  // Override the given registry hive using a randomly generated temporary key.
38  // Multiple overrides to the same hive are not supported and lead to undefined
39  // behavior.
40  void OverrideRegistry(HKEY override);
41
42 private:
43  friend class RegistryOverrideManagerTest;
44
45  // Keeps track of one override.
46  class ScopedRegistryKeyOverride {
47   public:
48    ScopedRegistryKeyOverride(HKEY override, const base::string16& key_path);
49    ~ScopedRegistryKeyOverride();
50
51   private:
52    HKEY override_;
53    base::win::RegKey temp_key_;
54
55    DISALLOW_COPY_AND_ASSIGN(ScopedRegistryKeyOverride);
56  };
57
58  // Used for testing only.
59  RegistryOverrideManager(const base::Time& timestamp,
60                          const base::string16& test_key_root);
61
62  base::Time timestamp_;
63  base::string16 guid_;
64
65  base::string16 test_key_root_;
66  ScopedVector<ScopedRegistryKeyOverride> overrides_;
67
68  DISALLOW_COPY_AND_ASSIGN(RegistryOverrideManager);
69};
70
71// Generates a temporary key path that will be eventually deleted
72// automatically if the process crashes.
73base::string16 GenerateTempKeyPath();
74
75}  // namespace registry_util
76
77#endif  // BASE_TEST_TEST_REG_UTIL_H_
78