tests/utils/test_decimal.py

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from decimal import Decimal

import pytest

from pyiceberg.utils.decimal import bytes_required, decimal_required_bytes, decimal_to_bytes


def test_decimal_required_bytes() -> None:
    assert decimal_required_bytes(precision=1) == 1
    assert decimal_required_bytes(precision=2) == 1
    assert decimal_required_bytes(precision=3) == 2
    assert decimal_required_bytes(precision=4) == 2
    assert decimal_required_bytes(precision=5) == 3
    assert decimal_required_bytes(precision=7) == 4
    assert decimal_required_bytes(precision=8) == 4
    assert decimal_required_bytes(precision=10) == 5
    assert decimal_required_bytes(precision=32) == 14
    assert decimal_required_bytes(precision=38) == 16

    with pytest.raises(ValueError) as exc_info:
        decimal_required_bytes(precision=40)
    assert "(0, 40]" in str(exc_info.value)

    with pytest.raises(ValueError) as exc_info:
        decimal_required_bytes(precision=-1)
    assert "(0, 40]" in str(exc_info.value)


def test_bytes_required() -> None:
    assert bytes_required(0) == 1
    assert bytes_required(127) == 1
    assert bytes_required(128) == 2
    # Check negative signed-byte boundaries and their neighbors.
    assert bytes_required(-127) == 1
    assert bytes_required(-128) == 1
    assert bytes_required(-129) == 2
    assert bytes_required(-32768) == 2
    assert bytes_required(-8388608) == 3
    assert bytes_required(Decimal("1.27")) == 1
    assert bytes_required(Decimal("-1.28")) == 1
    assert bytes_required(Decimal("-327.68")) == 2


def test_decimal_to_bytes() -> None:
    # Check the boundary between 2 and 3 bytes.
    # 2 bytes has a minimum of -32,768 and a maximum value of 32,767 (inclusive).
    assert decimal_to_bytes(Decimal("32767.")) == b"\x7f\xff"
    assert decimal_to_bytes(Decimal("32768.")) == b"\x00\x80\x00"
    # Unscaled values -128 and -32768 require no sign padding.
    assert decimal_to_bytes(Decimal("-1.28")) == b"\x80"
    assert decimal_to_bytes(Decimal("-327.68")) == b"\x80\x00"