Fix datetime before epoch on windows in cython implementation (#436)

Cython implementation still used datetime.from_timestamp method, which does not work on windows.
Update the cython implementation to use utc time and delta and add a regression test to highlight the issue.

1 files changed, 8 insertions, 0 deletions

diff --git a/test/test_timestamp.py b/test/test_timestamp.py
index 823fe04..edc488a 100644
--- a/test/test_timestamp.py
+++ b/test/test_timestamp.py
@@ -100,6 +100,14 @@ def test_unpack_datetime():
 
 
 @pytest.mark.skipif(sys.version_info[0] == 2, reason="datetime support is PY3+ only")
+def test_pack_unpack_before_epoch():
+    t_in = datetime.datetime(1960, 1, 1, tzinfo=_utc)
+    packed = msgpack.packb(t_in, datetime=True)
+    unpacked = msgpack.unpackb(packed, timestamp=3)
+    assert unpacked == t_in
+
+
+@pytest.mark.skipif(sys.version_info[0] == 2, reason="datetime support is PY3+ only")
 def test_pack_datetime():
     t = Timestamp(42, 14000)
     dt = t.to_datetime()