add assertions for res.tzinfo is expected.tzinfo

dateutil/test/test_parser.py

@@ -373,6 +373,7 @@ def test_valid_tzinfo_tzinfo_input(self):
         expected = datetime(2014, 1, 19, 9, tzinfo=tz.UTC)
         res = parse(dstr, tzinfos=tzinfos)
         assert res == expected
+        assert res.tzinfo is expected.tzinfo
 
     def test_valid_tzinfo_unicode_input(self):
         dstr = "2014 January 19 09:00 UTC"
@@ -390,6 +391,7 @@ def tzinfos(*args, **kwargs):
         expected = datetime(2014, 1, 19, 9, tzinfo=tz.tzstr("UTC+0"))
         res = parse(dstr, tzinfos=tzinfos)
         assert res == expected
+        assert res.tzinfo is expected.tzinfo
 
     @pytest.mark.xfail(reason="Doesn't check for UTC in tzinfos dict, "
                               "not sure it *should*.")
@@ -399,6 +401,7 @@ def test_valid_tzinfo_int_input(self):
         expected = datetime(2014, 1, 19, 9, tzinfo=tz.UTC)
         res = parse(dstr, tzinfos=tzinfos)
         assert res == expected
+        assert res.tzinfo is expected.tzinfo
 
 
 class ParserTest(unittest.TestCase):