update tests

Author: jbrockmendel

pandas/core/arrays/datetimelike.py

@@ -2070,6 +2070,8 @@ def _maybe_pin_freq(self, freq, validate_kwds: dict):
             # We cannot inherit a freq from the data, so we need to validate
             #  the user-passed freq
             freq = to_offset(freq)
+            if self.dtype.kind == "m":
+                freq = freq._maybe_to_hours()
             type(self)._validate_frequency(self, freq, **validate_kwds)
             self._freq = freq
         else:

pandas/tests/indexes/datetimes/methods/test_round.py

@@ -190,7 +190,7 @@ def test_ceil_floor_edge(self, test_input, rounder, freq, expected):
     )
     def test_round_int64(self, start, index_freq, periods, round_freq):
         dt = date_range(start=start, freq=index_freq, periods=periods)
-        unit = to_offset(round_freq).nanos
+        unit = to_offset(round_freq)._maybe_to_hours().nanos
 
         # test floor
         result = dt.floor(round_freq)

pandas/tests/indexes/datetimes/test_arithmetic.py

@@ -1,7 +1,6 @@
 # Arithmetic tests specific to DatetimeIndex are generally about `freq`
 #  rentention or inference.  Other arithmetic tests belong in
 #  tests/arithmetic/test_datetime64.py
-import pytest
 
 from pandas import (
     Timedelta,
@@ -16,28 +15,30 @@
 class TestDatetimeIndexArithmetic:
     def test_add_timedelta_preserves_freq(self):
         # GH#37295 should hold for any DTI with freq=None or Tick freq
+        # In pandas3 "D" preserves time-of-day across DST transitions, so
+        #  is not preserved by subtraction.  Ticks offsets like "24h"
+        #  are still preserved
         tz = "Canada/Eastern"
         dti = date_range(
             start=Timestamp("2019-03-26 00:00:00-0400", tz=tz),
             end=Timestamp("2020-10-17 00:00:00-0400", tz=tz),
-            freq="D",
+            freq="24h",
         )
         result = dti + Timedelta(days=1)
         assert result.freq == dti.freq
 
     def test_sub_datetime_preserves_freq(self, tz_naive_fixture):
         # GH#48818
-        dti = date_range("2016-01-01", periods=12, tz=tz_naive_fixture)
+        # In pandas3 "D" preserves time-of-day across DST transitions, so
+        #  is not preserved by subtraction.  Ticks offsets like "24h"
+        #  are still preserved
+        dti = date_range("2016-01-01", periods=12, tz=tz_naive_fixture, freq="24h")
 
         res = dti - dti[0]
         expected = timedelta_range("0 Days", "11 Days")
         tm.assert_index_equal(res, expected)
         assert res.freq == expected.freq
 
-    @pytest.mark.xfail(
-        reason="The inherited freq is incorrect bc dti.freq is incorrect "
-        "https://github.com/pandas-dev/pandas/pull/48818/files#r982793461"
-    )
     def test_sub_datetime_preserves_freq_across_dst(self):
         # GH#48818
         ts = Timestamp("2016-03-11", tz="US/Pacific")

pandas/tests/indexes/datetimes/test_misc.py

@@ -119,7 +119,7 @@ def test_datetimeindex_accessors(self):
             tm.assert_index_equal(res, exp)
 
     def test_datetimeindex_accessors2(self):
-        dti = date_range(freq="BQ-FEB", start=datetime(1998, 1, 1), periods=4)
+        dti = date_range(freq="BQE-FEB", start=datetime(1998, 1, 1), periods=4)
 
         assert sum(dti.is_quarter_start) == 0
         assert sum(dti.is_quarter_end) == 4
@@ -142,9 +142,9 @@ def test_datetimeindex_accessors4(self):
     def test_datetimeindex_accessors5(self):
         freq_m = to_offset("ME")
         bm = to_offset("BME")
-        qfeb = to_offset("Q-FEB")
+        qfeb = to_offset("QE-FEB")
         qsfeb = to_offset("QS-FEB")
-        bq = to_offset("BQ")
+        bq = to_offset("BQE")
         bqs_apr = to_offset("BQS-APR")
         as_nov = to_offset("YS-NOV")