BUG: Handle Period in combine (pandas-dev#23350)

Author: TomAugspurger

pandas/core/dtypes/cast.py

@@ -6,7 +6,7 @@
 import warnings
 
 from pandas._libs import tslib, lib, tslibs
-from pandas._libs.tslibs import iNaT, OutOfBoundsDatetime
+from pandas._libs.tslibs import iNaT, OutOfBoundsDatetime, Period
 from pandas.compat import string_types, text_type, PY3
 from .common import (ensure_object, is_bool, is_integer, is_float,
                      is_complex, is_datetimetz, is_categorical_dtype,
@@ -164,6 +164,12 @@ def trans(x):  # noqa
                     result = to_datetime(result).tz_localize('utc')
                     result = result.tz_convert(dtype.tz)
 
+        elif dtype.type == Period:
+            # TODO(DatetimeArray): merge with previous elif
+            from pandas.core.arrays import PeriodArray
+
+            return PeriodArray(result, freq=dtype.freq)
+
     except Exception:
         pass
 

pandas/tests/frame/test_combine_concat.py

@@ -759,7 +759,6 @@ def test_combine_first_timedelta(self):
         tm.assert_frame_equal(res, exp)
         assert res['TD'].dtype == 'timedelta64[ns]'
 
-    @pytest.mark.xfail(reason="GH-23079", strict=True)
     def test_combine_first_period(self):
         data1 = pd.PeriodIndex(['2011-01', 'NaT', '2011-03',
                                 '2011-04'], freq='M')