Function test_feather_format_compressed

python/pyarrow/tests/test_dataset.py:3740–3784

(tempdir, compression, dataset_reader)

    "brotli"  # not supported
])
def test_feather_format_compressed(tempdir, compression, dataset_reader):
    table = pa.table({'a': pa.array([0]*300, type="int8"),
                      'b': pa.array([.1, .2, .3]*100, type="float64")})
    if not pa.Codec.is_available(compression):
        pytest.skip()

    basedir = tempdir / "feather_dataset_compressed"
    basedir.mkdir()
    file_format = ds.IpcFileFormat()

    uncompressed_basedir = tempdir / "feather_dataset_uncompressed"
    uncompressed_basedir.mkdir()
    ds.write_dataset(
        table,
        str(uncompressed_basedir / "data.arrow"),
        format=file_format,
        file_options=file_format.make_write_options(compression=None)
    )

    if compression == "brotli":
        with pytest.raises(ValueError, match="Compression type"):
            write_options = file_format.make_write_options(
                compression=compression)
        with pytest.raises(ValueError, match="Compression type"):
            codec = pa.Codec(compression)
            write_options = file_format.make_write_options(compression=codec)
        return

    write_options = file_format.make_write_options(compression=compression)
    ds.write_dataset(
        table,
        str(basedir / "data.arrow"),
        format=file_format,
        file_options=write_options
    )

    dataset = ds.dataset(basedir, format=ds.IpcFileFormat())
    result = dataset_reader.to_table(dataset)
    assert result.equals(table)

    compressed_file = basedir / "data.arrow" / "part-0.arrow"
    compressed_size = compressed_file.stat().st_size
    uncompressed_file = uncompressed_basedir / "data.arrow" / "part-0.arrow"
    uncompressed_size = uncompressed_file.stat().st_size
    assert compressed_size < uncompressed_size


def _create_parquet_dataset_simple(root_path):