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import os
from concurrent.futures import ThreadPoolExecutor
from typing import Dict, Optional
from unittest import mock

import pytest

from pyiceberg.utils.concurrent import ExecutorFactory

EMPTY_ENV: Dict[str, Optional[str]] = {}
VALID_ENV = {"PYICEBERG_MAX_WORKERS": "5"}
INVALID_ENV = {"PYICEBERG_MAX_WORKERS": "invalid"}


def test_create_reused() -> None:
    first = ExecutorFactory.get_or_create()
    second = ExecutorFactory.get_or_create()
    assert isinstance(first, ThreadPoolExecutor)
    assert first is second


@mock.patch.dict(os.environ, EMPTY_ENV)
def test_max_workers_none() -> None:
    assert ExecutorFactory.max_workers() is None


@mock.patch.dict(os.environ, VALID_ENV)
def test_max_workers() -> None:
    assert ExecutorFactory.max_workers() == 5


@mock.patch.dict(os.environ, INVALID_ENV)
def test_max_workers_invalid() -> None:
    with pytest.raises(ValueError):
        ExecutorFactory.max_workers()