ScopedPrefSetter.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_gtest_ScopedPrefSetter_h

#define mozilla_gtest_ScopedPrefSetter_h

#include "mozilla/Assertions.h"

#include "mozilla/Attributes.h"

#include "mozilla/Preferences.h"

#include "nsThreadUtils.h"

namespace mozilla {

// Sets a boolean preference for the lifetime of the instance and restores the

// previous value on destruction, so a test does not leak its pref change into

// later tests. Must be constructed and destroyed on the main thread.

class MOZ_RAII ScopedPrefSetter {

 public:

  ScopedPrefSetter(const char* aPrefName, bool aValue)

      : mPrefName(aPrefName),

        mOriginalValue(Preferences::GetBool(aPrefName, false)) {

    MOZ_ASSERT(NS_IsMainThread());

    Preferences::SetBool(mPrefName, aValue);

  ~ScopedPrefSetter() {

    MOZ_ASSERT(NS_IsMainThread());

    Preferences::SetBool(mPrefName, mOriginalValue);

  ScopedPrefSetter(const ScopedPrefSetter&) = delete;

  ScopedPrefSetter& operator=(const ScopedPrefSetter&) = delete;

  ScopedPrefSetter(ScopedPrefSetter&&) = delete;

  ScopedPrefSetter& operator=(ScopedPrefSetter&&) = delete;

 private:

  const char* mPrefName;

  const bool mOriginalValue;

};

}  // namespace mozilla

#endif  // mozilla_gtest_ScopedPrefSetter_h