def test_many_columns_non_petastorm_dataset(many_columns_non_petastorm_dataset, reader_factory):
    """Check if we can read a dataset with huge number of columns (1000 in this case)"""
    with reader_factory(many_columns_non_petastorm_dataset.url) as reader:
        sample = next(reader)
        assert set(sample._fields) == set(many_columns_non_petastorm_dataset.data[0].keys())
Check if we can read a dataset with huge number of columns (1000 in this case)
petastorm/tests/test_parquet_reader.py