#[test]
fn statistics_null_counts_only_nulls() {
    // check that null-count statistics for "only NULL"-columns are correct
    let values = Arc::new(UInt64Array::from(vec![
        None,
        None,
    ]));
    let file = one_column_roundtrip("null_counts", values, true);

    // check statistics are valid
    let reader = SerializedFileReader::new(file).unwrap();
    let metadata = reader.metadata();
    assert_eq!(metadata.num_row_groups(), 1);
    let row_group = metadata.row_group(0);
    assert_eq!(row_group.num_columns(), 1);
    let column = row_group.column(0);
    let stats = column.statistics().unwrap();
    assert_eq!(stats.null_count(), 2);  // <<< this fails, null count is 0
}