chromium/base/test/mock_log.h

// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_TEST_MOCK_LOG_H_
#define BASE_TEST_MOCK_LOG_H_

#include <stddef.h>

#include <string>

#include "base/logging.h"
#include "base/synchronization/lock.h"
#include "testing/gmock/include/gmock/gmock.h"

namespace base {
namespace test {

// A MockLog object intercepts LOG() messages issued during its lifespan.  Using
// this together with gMock, it's very easy to test how a piece of code calls
// LOG().  The typical usage:
//
//   TEST(FooTest, LogsCorrectly) {
//     MockLog log;
//
//     // We expect the WARNING "Something bad!" exactly twice.
//     EXPECT_CALL(log, Log(WARNING, _, "Something bad!"))
//         .Times(2);
//
//     // We allow foo.cc to call LOG(INFO) any number of times.
//     EXPECT_CALL(log, Log(INFO, HasSubstr("/foo.cc"), _))
//         .Times(AnyNumber());
//
//     log.StartCapturingLogs();  // Call this after done setting expectations.
//     Foo();  // Exercises the code under test.
//   }
//
// CAVEAT: base/logging does not allow a thread to call LOG() again when it's
// already inside a LOG() call.  Doing so will cause a deadlock.  Therefore,
// it's the user's responsibility to not call LOG() in an action triggered by
// MockLog::Log().  You may call RAW_LOG() instead.
class MockLog { … };

}  // namespace test
}  // namespace base

#endif  // BASE_TEST_MOCK_LOG_H_