TST: xfails unary neg on series period

Author: deniederhut

pandas/tests/series/test_arithmetic.py

@@ -305,6 +305,8 @@ def test_ops_series_timedelta(self):
         result = pd.tseries.offsets.Day() + ser
         tm.assert_series_equal(result, expected)
 
+    @pytest.mark.xfail(reason="Unary negative is currently not permitted "
+                          "for objects of type TimePeriod, see GH 19297")
     def test_ops_series_period(self):
         # GH 13043
         ser = pd.Series([pd.Period('2015-01-01', freq='D'),