def METHOD_NAME(tmpdir):
    from datacube.ui.task_app import validate_cell_index, validate_cell_list, cell_list_to_file
    assert validate_cell_index(None, None, None) is None
    assert validate_cell_index(None, None, '17,-12') == (17, -12)
    cell_list = [(17, 12), (16, -10), (-23, 0)]
    cell_list_file = tmpdir.join('cell_list.txt')
    if cell_list_file.exists():
        cell_list_file.unlink()
    assert not cell_list_file.check()
    cell_list_to_file(str(cell_list_file), cell_list)
    assert cell_list_file.check()
    assert validate_cell_list(None, None, None) is None
    assert validate_cell_list(None, None, str(cell_list_file)) == cell_list