Previously failed tests paassing

let's see what's broken now.

Author: kirkhansen

pandas/core/indexes/datetimelike.py

@@ -31,7 +31,6 @@
 
 from pandas.tseries.offsets import index_offsets_equal
 import pandas.tseries.frequencies as frequencies
-import pandas.core.indexes.api as _api
 
 _index_doc_kwargs = dict(ibase._index_doc_kwargs)
 
@@ -635,8 +634,7 @@ def intersection(self, other):
         self._assert_can_do_setop(other)
 
         if self.equals(other):
-            name = _api._get_consensus_names((self, other))[0]
-            return self._shallow_copy(self, name=name)
+            return self._get_reconciled_name_object(other)
 
         lengths = len(self), len(other)
         if lengths[0] == 0:
@@ -645,21 +643,25 @@ def intersection(self, other):
             return other
 
         if (not index_offsets_equal(self, other) or
+           not other.freq.isAnchored() or  # Fixes period intersections when freq is set
            (not self._is_strictly_monotonic or
                 not other._is_strictly_monotonic)):
             result = Index.intersection(self, other)
+            if result.empty:
+                result = result.astype(self.dtype)
             result = self._shallow_copy(result._values, name=result.name,
                                         freq=None
                                         )
             if result.freq is None:
                 result.offset = frequencies.to_offset(result.inferred_freq)
+                # attempt a naive guess at the freq.
+                result.freq = self.freq or other.freq
             return result
 
         # Conditions met!
         intersected_slice = self._fast_intersection(other)
-        name = _api._get_consensus_names((self, other))[0]
-        intersected = self._shallow_copy(intersected_slice, name=name)
-        return intersected
+        name = ops.get_op_result_name(self, other)
+        return self._shallow_copy(intersected_slice, name=name)
 
 def wrap_arithmetic_op(self, other, result):
     if result is NotImplemented:

pandas/core/indexes/period.py

@@ -723,7 +723,7 @@ def _maybe_cast_slice_bound(self, label, side, kind):
         Value of `side` parameter should be validated in caller.
 
         """
-        assert kind in ['ix', 'loc', 'getitem']
+        assert kind in ['ix', 'loc', 'getitem', None]
 
         if isinstance(label, datetime):
             return Period(label, freq=self.freq)

pandas/tests/indexes/datetimes/test_setops.py

@@ -133,7 +133,7 @@ def test_intersection2(self):
 
         third = Index(['a', 'b', 'c'])
         result = first.intersection(third)
-        expected = pd.Index([], dtype=object)
+        expected = DatetimeIndex([])
         tm.assert_index_equal(result, expected)
 
     @pytest.mark.parametrize("tz", [None, 'Asia/Tokyo', 'US/Eastern',
@@ -151,7 +151,7 @@ def test_intersection(self, tz):
         expected3 = date_range('6/1/2000', '6/20/2000', freq='D', name=None)
 
         rng4 = date_range('7/1/2000', '7/31/2000', freq='D', name='idx')
-        expected4 = DatetimeIndex([], name='idx')
+        expected4 = DatetimeIndex([], name='idx', freq='D')
 
         for (rng, expected) in [(rng2, expected2), (rng3, expected3),
                                 (rng4, expected4)]:
@@ -181,14 +181,14 @@ def test_intersection(self, tz):
         # GH 7880
         rng4 = date_range('7/1/2000', '7/31/2000', freq='D', tz=tz,
                           name='idx')
-        expected4 = DatetimeIndex([], tz=tz, name='idx')
+        expected4 = DatetimeIndex([], tz=tz, name='idx', freq='D')
 
         for (rng, expected) in [(rng2, expected2), (rng3, expected3),
                                 (rng4, expected4)]:
             result = base.intersection(rng)
             tm.assert_index_equal(result, expected)
             assert result.name == expected.name
-            assert result.freq is None
+            assert result.freq == expected.freq
             assert result.tz == expected.tz
 
     def test_intersection_empty(self):