from app.core.cron_utils import CronValidationError, describe_cron_expression, preview_next_runs, validate_cron_expression


def test_validate_cron_expression_accepts_daily_schedule():
    validate_cron_expression('15 2 * * *', 'Europe/Warsaw')


def test_validate_cron_expression_rejects_invalid_schedule():
    try:
        validate_cron_expression('bad cron', 'Europe/Warsaw')
    except CronValidationError:
        assert True
        return
    assert False, 'invalid cron should raise'


def test_preview_next_runs_returns_future_datetimes():
    runs = preview_next_runs('0 3 * * 1', 'Europe/Warsaw', count=2)
    assert len(runs) == 2
    assert runs[0] < runs[1]


def test_describe_cron_expression_humanizes_common_patterns():
    assert describe_cron_expression('0 2 * * *') == 'Every day at 02:00'