custom clock and noncastable tests

test/clock_cast_test/local_t.pass.cpp

@@ -0,0 +1,103 @@
+#include <chrono>
+#include "date/tz.h"
+
+int
+main()
+{
+   using namespace date;
+   using namespace std::chrono;
+
+   // self
+   {
+     auto ls = local_days{1970_y/01/01_d};
+     assert(clock_cast<local_t>(ls) == ls);
+   }
+
+   /// sys epoch 
+   {
+     auto ls = local_days{1970_y/01/01_d};
+     auto st = clock_cast<system_clock>(ls);
+     assert(clock_cast<local_t>(st) == ls);
+     assert(st.time_since_epoch() == seconds(0));
+   }
+
+   /// sys 2000 case 
+   {
+     auto ls = local_days{2000_y/01/01_d};
+     auto st = clock_cast<system_clock>(ls);
+     assert(clock_cast<local_t>(st) == ls);
+     assert(st.time_since_epoch() == seconds(946684800));
+   }
+
+
+   /// utc epoch 
+   {
+     auto lu = local_days{1970_y/01/01_d};
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<local_t>(ut) == lu);
+     assert(ut.time_since_epoch() == seconds(0));
+   }
+
+   /// utc paper example 
+   {
+     auto lu = local_days{2000_y/01/01_d};
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<local_t>(ut) == lu);
+     assert(ut.time_since_epoch() == seconds(946684822));
+   }
+
+   /// tai epoch
+   {
+     auto lt = local_days{1958_y/01/01_d};
+     auto tt = clock_cast<tai_clock>(lt);
+     assert(clock_cast<local_t>(tt) == lt);
+     assert(tt.time_since_epoch() == seconds(0));
+
+     auto lu = local_days{1958_y/01/01_d} - seconds(10);
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<tai_clock>(ut) == tt);
+   }
+
+   // tai paper example
+   {
+      auto lt = local_days{2000_y/01/01_d} + seconds(32);
+      auto tt = clock_cast<tai_clock>(lt);
+      assert(clock_cast<local_t>(tt) == lt);
+
+      auto lu = local_days{2000_y/01/01_d};
+      auto ut = clock_cast<utc_clock>(lu);
+      assert(clock_cast<tai_clock>(ut) == tt);
+   }
+
+   /// gps epoch
+   {
+     auto lg = local_days{1980_y/01/Sunday[1]};
+     auto gt = clock_cast<gps_clock>(lg);
+     assert(clock_cast<local_t>(gt) == lg);
+     assert(gt.time_since_epoch() == seconds(0));
+
+     auto lu = local_days{1980_y/01/Sunday[1]};
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<gps_clock>(ut) == gt);
+
+     auto lt = local_days{1980_y/01/Sunday[1]} + seconds(19);
+     auto tt = clock_cast<tai_clock>(lt);
+     assert(clock_cast<gps_clock>(tt) == gt);
+   }
+
+   // gps 2000 example
+   {
+     auto lg = local_days{2000_y/01/01_d};
+     auto gt = clock_cast<gps_clock>(lg);
+     assert(clock_cast<local_t>(gt) == lg);
+
+     auto lu = local_days{2000_y/01/01_d} - seconds(13);
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<gps_clock>(ut) == gt);
+
+     auto lt = local_days{2000_y/01/01_d} + seconds(19);
+     auto tt = clock_cast<tai_clock>(lt);
+     assert(clock_cast<gps_clock>(tt) == gt);
+   }
+
+}