diff --git a/pandas/tests/indexing/multiindex/test_setitem.py b/pandas/tests/indexing/multiindex/test_setitem.py index d732cb4d7fbbc..615a0eb6e1af1 100644 --- a/pandas/tests/indexing/multiindex/test_setitem.py +++ b/pandas/tests/indexing/multiindex/test_setitem.py @@ -490,6 +490,24 @@ def test_setitem_enlargement_keep_index_names(self): ) tm.assert_frame_equal(df, expected) + def test_setitem_enlargement_multiindex_with_none(self): + # GH#59153 + # enlarging a DataFrame with a MultiIndex containing None values + index = MultiIndex.from_tuples( + [("A", "a1"), ("A", "a2"), ("B", "b1"), ("B", None)] + ) + df = DataFrame([(0.0, 6.0), (1.0, 5.0), (2.0, 4.0), (3.0, 7.0)], index=index) + df.loc[("A", None), :] = [12.0, 13.0] + expected_index = MultiIndex.from_tuples( + [("A", "a1"), ("A", "a2"), ("B", "b1"), ("B", None), ("A", None)] + ) + expected = DataFrame( + [[0.0, 6.0], [1.0, 5.0], [2.0, 4.0], [3.0, 7.0], [12.0, 13.0]], + index=expected_index, + columns=[0, 1], + ) + tm.assert_frame_equal(df, expected, check_index_type=False) + def test_frame_setitem_view_direct(multiindex_dataframe_random_data): # this works because we are modifying the underlying array