libcxx/test/std/time/time.clock/time.clock.file/to_from_sys.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // UNSUPPORTED: availability-filesystem-missing
  12
  13 // <chrono>
  14 //
  15 // file_clock
  16 //
  17 // template<class Duration>
  18 // static sys_time<see-below> to_sys(const file_time<Duration>&);
  19 //
  20 // template<class Duration>
  21 // static file_time<see-below> from_sys(const sys_time<Duration>&);
  22
  23 #include <chrono>
  24 #include <cassert>
  25
  26 int main(int, char**) {
  27   // Test round-trip through the system clock, starting from file_clock::now()
  28   {
  29     std::chrono::file_clock::time_point const ft = std::chrono::file_clock::now();
  30     auto st = std::chrono::file_clock::to_sys(ft);
  31     assert(ft == std::chrono::file_clock::from_sys(st));
  32   }
  33
  34   // Test round-trip through the system clock, starting from system_clock::now()
  35   {
  36     std::chrono::system_clock::time_point const st = std::chrono::system_clock::now();
  37     auto ft = std::chrono::file_clock::from_sys(st);
  38     assert(st == std::chrono::file_clock::to_sys(ft));
  39   }
  40
  41   // Make sure the value we get is in the ballpark of something reasonable
  42   {
  43     std::chrono::file_clock::time_point const file_now = std::chrono::file_clock::now();
  44     std::chrono::system_clock::time_point const sys_now = std::chrono::system_clock::now();
  45     {
  46       auto diff = sys_now - std::chrono::file_clock::to_sys(file_now);
  47       assert(std::chrono::milliseconds(-500) < diff && diff < std::chrono::milliseconds(500));
  48     }
  49     {
  50       auto diff = std::chrono::file_clock::from_sys(sys_now) - file_now;
  51       assert(std::chrono::milliseconds(-500) < diff && diff < std::chrono::milliseconds(500));
  52     }
  53   }
  54
  55   // Make sure to_sys and from_sys are consistent with each other
  56   {
  57     std::chrono::file_clock::time_point const ft = std::chrono::file_clock::now();
  58     std::chrono::system_clock::time_point const st = std::chrono::system_clock::now();
  59     auto sys_diff = std::chrono::file_clock::to_sys(ft) - st;
  60     auto file_diff = ft - std::chrono::file_clock::from_sys(st);
  61     assert(sys_diff == file_diff);
  62   }
  63
  64   return 0;
  65 }