def METHOD_NAME(
    us, precision, precision_constraint, expected_truncated_us,
):
    # complete the datetime string with microseconds
    dt_us_str = "{}.{:06d}Z".format(_DT_STR, us)
    sdt = parse_into_datetime(
        dt_us_str,
        precision=precision,
        precision_constraint=precision_constraint,
    )
    assert sdt.precision is precision
    assert sdt.precision_constraint is precision_constraint
    assert sdt.microsecond == expected_truncated_us