address comments

Author: juleek

doc/source/whatsnew/v2.0.0.rst

@@ -1371,8 +1371,7 @@ Groupby/resample/rolling
 - Bug in :meth:`.DataFrameGroupBy.agg` with ``engine="numba"`` failing to respect ``as_index=False`` (:issue:`51228`)
 - Bug in :meth:`DataFrameGroupBy.agg`, :meth:`SeriesGroupBy.agg`, and :meth:`Resampler.agg` would ignore arguments when passed a list of functions (:issue:`50863`)
 - Bug in :meth:`DataFrameGroupBy.ohlc` ignoring ``as_index=False`` (:issue:`51413`)
-- Bug in :meth:`BaseGrouper.groups` when grouping by datetime, zip() was using :meth:`BaseGrouper.__iter__` that produced incorrect result in case of :class:`BinGrouper`. Fixed by adding :meth:`BinGrouper.__iter__` that returns correct iterable (:issue:`51158`)
--
+- Bug in :meth:`GroupBy.groups` with a datetime key in conjunction with another key produced incorrect number of group keys (:issue:`51158`)
 
 Reshaping
 ^^^^^^^^^

pandas/tests/groupby/test_grouping.py

@@ -451,7 +451,7 @@ def test_groupby_with_datetime_key(self):
             }
         )
         grouper = Grouper(key="b", freq="D")
-        g = df.groupby([grouper, "id"])
+        gb = df.groupby([grouper, "id"])
 
         # test number of groups
         expected = {
@@ -460,10 +460,10 @@ def test_groupby_with_datetime_key(self):
             (Timestamp("2000-01-02"), "a"): [4],
             (Timestamp("2000-01-02"), "b"): [3, 5],
         }
-        tm.assert_dict_equal(g.groups, expected)
+        tm.assert_dict_equal(gb.groups, expected)
 
         # test number of group keys
-        tm.assert_equal(len(g.groups.keys()), 4)
+        assert len(gb.groups.keys()) == 4
 
     def test_grouping_error_on_multidim_input(self, df):
         msg = "Grouper for '<class 'pandas.core.frame.DataFrame'>' not 1-dimensional"