def multiply(a, b):
    """
    计算两个数字的乘积

    Args:
        a: 第一个数字
        b: 第二个数字

    Returns:
        两个数字的乘积
    """
    return a * b

def divide(a, b):
    """
    计算两个数字的商

    Args:
        a: 被除数
        b: 除数

    Returns:
        两个数字的商

    Raises:
        ValueError: 如果除数为零
    """
    if b == 0:
        raise ValueError("除数不能为零")
    return a / b

if __name__ == "__main__":
    # 测试乘法函数
    print("测试乘法函数:")
    test_cases_multiply = [
        (2, 3, 6),
        (-2, 3, -6),
        (0, 5, 0),
        (2.5, 4, 10.0),
        (-2.5, -2, 5.0)
    ]

    for a, b, expected in test_cases_multiply:
        result = multiply(a, b)
        status = "PASS" if result == expected else "FAIL"
        print(f"  {status} multiply({a}, {b}) = {result} (期望: {expected})")

    # 测试除法函数
    print("\n测试除法函数:")
    test_cases_divide = [
        (6, 3, 2),
        (10, 2, 5),
        (-6, 2, -3),
        (5, 2, 2.5),
        (0, 5, 0)
    ]

    for a, b, expected in test_cases_divide:
        try:
            result = divide(a, b)
            status = "PASS" if result == expected else "FAIL"
            print(f"  {status} divide({a}, {b}) = {result} (期望: {expected})")
        except ValueError as e:
            print(f"  FAIL divide({a}, {b}) 出错: {e}")

    # 测试除数为零的情况
    print("\n测试除数为零:")
    try:
        divide(5, 0)
        print("  FAIL divide(5, 0) 应该抛出异常但没有")
    except ValueError as e:
        print(f"  PASS divide(5, 0) 正确抛出异常: {e}")