test: tests/no_imports_test.py::test_pyarrow may randomly fail

[MarcoGorelli]

Check this out:

(polars-api-compat-dev) marcogorelli@DESKTOP-U8OKFP3:~/polars-api-compat-dev$ pytest tests/no_imports_test.py 
=========================================== test session starts ===========================================
platform linux -- Python 3.12.9, pytest-8.3.5, pluggy-1.5.0
Using --randomly-seed=1694143034
rootdir: /home/marcogorelli/polars-api-compat-dev
configfile: pyproject.toml
plugins: anyio-4.9.0, env-1.1.5, cov-6.1.1, randomly-3.16.0, hypothesis-6.130.12
collected 4 items                                                                                         

tests/no_imports_test.py ..F.                                                                       [100%]

================================================ FAILURES =================================================
______________________________________________ test_pyarrow _______________________________________________

monkeypatch = <_pytest.monkeypatch.MonkeyPatch object at 0x7f8575198da0>

    def test_pyarrow(monkeypatch: pytest.MonkeyPatch) -> None:
        pytest.importorskip("pyarrow")
        import pyarrow as pa
    
        monkeypatch.delitem(sys.modules, "polars", raising=False)
        monkeypatch.delitem(sys.modules, "pandas")
        monkeypatch.delitem(sys.modules, "duckdb", raising=False)
        monkeypatch.delitem(sys.modules, "dask", raising=False)
        monkeypatch.delitem(sys.modules, "ibis", raising=False)
        monkeypatch.delitem(sys.modules, "pyspark", raising=False)
        df = pa.table({"a": [1, 2, 3], "b": [4, 5, 6]})
        nw.from_native(df).group_by("a").agg(nw.col("b").mean()).filter(nw.col("a") > 1)
        assert "polars" not in sys.modules
>       assert "pandas" not in sys.modules
E       AssertionError: assert 'pandas' not in {'__future__': <module '__future__' from '/usr/lib/python3.12/__future__.py'>, '__main__': <module '__main__' from '/h... '__main__' from '/home/marcogorelli/polars-api-compat-dev/.venv/bin/pytest'>, '_abc': <module '_abc' (built-in)>, ...}
E        +  where {'__future__': <module '__future__' from '/usr/lib/python3.12/__future__.py'>, '__main__': <module '__main__' from '/h... '__main__' from '/home/marcogorelli/polars-api-compat-dev/.venv/bin/pytest'>, '_abc': <module '_abc' (built-in)>, ...} = sys.modules

tests/no_imports_test.py:89: AssertionError
========================================= short test summary info =========================================
FAILED tests/no_imports_test.py::test_pyarrow - AssertionError: assert 'pandas' not in {'__future__': <module '__future__' from '/usr/lib/python3.12/_...
======================================= 1 failed, 3 passed in 1.45s =======================================
(polars-api-compat-dev) marcogorelli@DESKTOP-U8OKFP3:~/polars-api-compat-dev$ pytest tests/no_imports_test.py 
=============================================================== test session starts ===============================================================
platform linux -- Python 3.12.9, pytest-8.3.5, pluggy-1.5.0
Using --randomly-seed=4003032099
rootdir: /home/marcogorelli/polars-api-compat-dev
configfile: pyproject.toml
plugins: anyio-4.9.0, env-1.1.5, cov-6.1.1, randomly-3.16.0, hypothesis-6.130.12
collected 4 items                                                                                                                                 

tests/no_imports_test.py ....                                                                                                               [100%]

================================================================ 4 passed in 0.78s ================================================================

🤷 no idea why

maybe we should look into a solution like https://stackoverflow.com/a/65163627/4451315 ?

[dangotbanned]

Since there were 4 tests collected, does this fail when 1 of them imports pandas and runs before the pyarrow test?