Unit test and typo fix

include/date/tz.h

@@ -2344,7 +2344,7 @@ struct clock_time_conversion<std::chrono::system_clock, local_t>
     sys_time<Duration>
     operator()(const local_time<Duration>& lt) const
     {
-        return sys_time<Duration>{lt.time_sine_epoch()};
+        return sys_time<Duration>{lt.time_since_epoch()};
     }
 };
 

test/tz_test/local_time_conversion.pass.cpp

@@ -0,0 +1,98 @@
+#include <chrono>
+#include "date/tz.h"
+
+int
+main()
+{
+   using namespace date;
+   using namespace std::chrono_literals;
+   using namespace std::chrono;
+
+   /// 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() == 0s);
+   }
+
+   /// 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() == 946'684'800s);
+   }
+
+
+   /// 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() == 0s);
+   }
+
+   /// 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() == 946'684'822s);
+   }
+
+   /// 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() == 0s);
+
+     auto lu = local_days{1957_y/12/31_d} + 23h + 59min + 50s;
+     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} + 32s;
+      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() == 0s);
+
+     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]} + 19s;
+     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} - 13s;
+     auto ut = clock_cast<utc_clock>(lu);
+     assert(clock_cast<gps_clock>(ut) == gt);
+
+     auto lt = local_days{2000_y/01/01_d} + 19s;
+     auto tt = clock_cast<tai_clock>(lt);
+     assert(clock_cast<gps_clock>(tt) == gt);
+   }
+
+}