log_capture_fixture.hpp

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#pragma once
 
/// @file userver/utest/log_capture_fixture.hpp
/// @brief @copybrief utest::LogCaptureFixture
/// @ingroup userver_universal
 
#include <iosfwd>
#include <optional>
#include <string>
#include <string_view>
#include <utility>
#include <vector>
 
#include <gtest/gtest.h>
 
#include <userver/logging/impl/logger_base.hpp>
#include <userver/logging/level.hpp>
#include <userver/logging/log.hpp>
#include <userver/utest/default_logger_fixture.hpp>
#include <userver/utils/function_ref.hpp>
#include <userver/utils/impl/internal_tag.hpp>
#include <userver/utils/impl/source_location.hpp>
#include <userver/utils/not_null.hpp>
#include <userver/utils/span.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace utest {
 
namespace impl {
class ToStringLogger;
}  // namespace impl
 
/// @ingroup userver_utest
///
/// @brief Represents single log record, typically written via `LOG_*` macros.
///
/// @see @ref utest::LogCaptureLogger
/// @see @ref utest::LogCaptureFixture
class LogRecord final {
public:
    /// @returns decoded text of the log record
    /// @throws if no 'text' tag in the log
    const std::string& GetText() const;
 
    /// @returns decoded value of the tag in the log record
    /// @throws if no such tag in the log
    const std::string& GetTag(std::string_view key) const;
 
    /// @returns decoded value of the tag in the log record, or `std::nullopt`
    std::optional<std::string> GetTagOptional(std::string_view key) const;
 
    /// @returns decoded value of the tag in the log record, or `nullptr`
    const std::string* GetTagOrNullptr(std::string_view key) const;
 
    /// @returns serialized log record
    const std::string& GetLogRaw() const;
 
    /// @returns the log level of the record
    logging::Level GetLevel() const;
 
    /// @cond
    // For internal use only.
    LogRecord(utils::impl::InternalTag, logging::Level level, std::string&& log_raw);
    /// @endcond
 
private:
    logging::Level level_;
    std::string log_raw_;
    std::vector<std::pair<std::string, std::string>> tags_;
};
 
std::ostream& operator<<(std::ostream&, const LogRecord& data);
 
std::ostream& operator<<(std::ostream&, const std::vector<LogRecord>& data);
 
/// Thrown by @ref GetSingleLog.
class NotSingleLogError final : public std::runtime_error {
public:
    using std::runtime_error::runtime_error;
};
 
/// @returns the only log record from `log`.
/// @throws NotSingleLogError if there are zero or multiple log records.
LogRecord GetSingleLog(
    utils::span<const LogRecord> log,
    const utils::impl::SourceLocation& source_location = utils::impl::SourceLocation::Current()
);
 
/// @ingroup userver_utest
///
/// @brief A mocked logger that stores the log records in memory.
///
/// @snippet grpc/tests/cancel_test.cpp  Sample of LogCaptureFixture
///
/// @see @ref utest::LogCaptureFixture
class LogCaptureLogger final {
public:
    explicit LogCaptureLogger(logging::Format format = logging::Format::kRaw);
 
    /// @returns the mocked logger.
    logging::TextLoggerPtr GetLogger() const;
 
    /// @returns all collected logs.
    /// @see @ref GetSingleLog
    std::vector<LogRecord> GetAll() const;
 
    /// @returns logs filtered by (optional) text substring and (optional) tags substrings.
    /// @see @ref GetSingleLog
    std::vector<LogRecord> Filter(
        std::string_view text_substring,
        utils::span<const std::pair<std::string_view, std::string_view>> tag_substrings = {}
    ) const;
 
    /// @returns logs filtered by an arbitrary predicate.
    /// @see @ref GetSingleLog
    std::vector<LogRecord> Filter(utils::function_ref<bool(const LogRecord&)> predicate) const;
 
    /// @brief Discards the collected logs.
    void Clear() noexcept;
 
    /// @brief Logs @a value as-if using `LOG_*`, then extracts the log text.
    template <typename T>
    std::string ToStringViaLogging(const T& value) {
        Clear();
        LOG_CRITICAL() << value;
        auto text = GetSingleLog(GetAll()).GetText();
        Clear();
        return text;
    }
 
private:
    utils::SharedRef<impl::ToStringLogger> logger_;
};
 
/// @ingroup userver_utest
///
/// @brief Fixture that allows to capture and extract log written into the default logger.
///
/// @snippet grpc/tests/cancel_test.cpp  Sample of LogCaptureFixture
///
/// @see @ref utest::LogCaptureLogger
template <typename Base = ::testing::Test>
class LogCaptureFixture : public DefaultLoggerFixture<Base> {
protected:
    LogCaptureFixture() { DefaultLoggerFixture<Base>::SetDefaultLogger(logger_.GetLogger()); }
 
    /// @returns logger that holds the log records of the unit test
    LogCaptureLogger& GetLogCapture() { return logger_; }
 
private:
    LogCaptureLogger logger_;
};
 
}  // namespace utest
 
USERVER_NAMESPACE_END