| // Copyright 2019 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "platform/api/time.h" |
| |
| #include <chrono> |
| #include <ctime> |
| |
| #include "gtest/gtest.h" |
| #include "util/chrono_helpers.h" |
| |
| namespace openscreen { |
| |
| #if __cplusplus < 202000L |
| // Before C++20, the standard does not guarantee that time_t is the number of |
| // seconds since the UNIX epoch. It also doesn't guarantee that one tick of |
| // time_t represents one second. However, this is so universally common, it's |
| // worth assuming the platform provides this. |
| TEST(TimeTest, TimeTMeetsTheCpp20Standard) { |
| // Use the functions the standard *does* provide for calendar time |
| // conversions to determine the value of time_t at the UNIX epoch. |
| std::tm epoch_tm; |
| epoch_tm.tm_sec = 0; |
| epoch_tm.tm_min = 0; |
| epoch_tm.tm_hour = 0; |
| epoch_tm.tm_mday = 1; |
| epoch_tm.tm_mon = 0; |
| epoch_tm.tm_year = 70; // 1970 |
| epoch_tm.tm_isdst = 0; |
| // Note: std::mktime() assumes the translation is in the local time zone. |
| const std::time_t new_year_1970_in_local_tz = std::mktime(&epoch_tm); |
| // Purposely misinterpret |new_year_1970_in_local_tz| as UTC to provide |
| // information as to how to offset |epoch_tm| such that std::mktime() will |
| // be fooled into returning the value in terms of UTC. |
| std::tm* const wrong_tm = std::gmtime(&new_year_1970_in_local_tz); |
| epoch_tm.tm_sec += epoch_tm.tm_sec - wrong_tm->tm_sec; |
| epoch_tm.tm_min += epoch_tm.tm_min - wrong_tm->tm_min; |
| epoch_tm.tm_hour += epoch_tm.tm_hour - wrong_tm->tm_hour; |
| epoch_tm.tm_mday += epoch_tm.tm_mday - wrong_tm->tm_mday; |
| epoch_tm.tm_mon += epoch_tm.tm_mon - wrong_tm->tm_mon; |
| epoch_tm.tm_year += epoch_tm.tm_year - wrong_tm->tm_year; |
| |
| const std::time_t epoch = std::mktime(&epoch_tm); |
| EXPECT_EQ(seconds(0), seconds(epoch)); |
| |
| ++epoch_tm.tm_sec; |
| const std::time_t epoch_plus_one_second = std::mktime(&epoch_tm); |
| EXPECT_EQ(seconds(1), seconds(epoch_plus_one_second)); |
| } |
| #endif |
| |
| } // namespace openscreen |