[Python] Pandas integration TestConvertMetadata.test_table_column_subset_metadata fails with nightlies pandas

[raulcd]

Describe the bug, including details regarding any error messages, version, and platform.

CI nightly jobs for pandas and numpy nightly/devel:

• test-conda-python-3.13-pandas-nightly-numpy-nightly
• test-conda-python-3.13-pandas-upstream_devel-numpy-nightly

have been failing with the following test failure for approximately 1 week:

____________ TestConvertMetadata.test_table_column_subset_metadata _____________

self = <pyarrow.tests.test_pandas.TestConvertMetadata object at 0x7f7bbc3253e0>

    def test_table_column_subset_metadata(self):
        # ARROW-1883
        # non-default index
        for index in [
                pd.Index(['a', 'b', 'c'], name='index'),
                pd.date_range("2017-01-01", periods=3, tz='Europe/Brussels')]:
            df = pd.DataFrame({'a': [1, 2, 3],
                               'b': [.1, .2, .3]}, index=index)
            table = pa.Table.from_pandas(df)
    
            table_subset = table.remove_column(1)
            result = table_subset.to_pandas()
            expected = df[['a']]
            if isinstance(df.index, pd.DatetimeIndex):
                df.index.freq = None
>           tm.assert_frame_equal(result, expected)
E           AssertionError: (None, <Day>)

Component(s)

Python

[raulcd]

@jorisvandenbossche any idea of any pandas commit that can be the culprit of this?

[AnkitAhlawat7742]

Hi @raulcd and @jorisvandenbossche,

This issue is the same as #49920. I have already investigated and identified the root cause — the pandas change in pandas-dev/pandas#65429 made freq Index-only state. The test was incorrectly setting df.index.freq = None instead of expected.index.freq = None since expected = df[["a"]] creates an independent Index object. I have tested the fix locally and it passes. Please let me know if my investigation is correct and i can update the test case. if you guys agree

[raulcd]

Sorry, I did not realized there was a different issue opened with the investigation.
I am not entirely sure @AnkitAhlawat7742 as I don't understand this code in depth, can you submit a PR with your proposed patch? we can discuss further there.