基于c++的完全数之TDD版本

#include <iostream>
#include <cassert>
#include <cmath>

using namespace std;

//完全数，真因子之和等于该数
//1.需要判断一个数是否为因子
//2.需要获得所有真因子之和
//3.需要判断是否是完全数

bool is_factor(int factor, int num)
{
    return num % factor == 0;
}

static int add_factor(int factor, int num)
{
    return factor + num / factor;
}

static int cal_aliquot_sum(int num)
{
    int sum = 1;
    for (int i = 2; i <= (int)sqrt((double)num); i++)
    {
        if (is_factor(i, num))
        {
            sum += add_factor(i, num);
        }
    }
    return sum;
}

int aliquot_sum(int num)
{
    int sum = 0;
    if (num > 0)
    {
        sum = cal_aliquot_sum(num);
    }
    return sum;
}

bool is_perfect(int num)
{
    return aliquot_sum(num) == num;
}

bool is_abundant(int num)
{
    return aliquot_sum(num) > num;
}

bool is_deficient(int num)
{
    return aliquot_sum(num) < num;
}

/* ------------------------------- */
void test_1_is_factor_of_10()
{
    assert(is_factor(1, 10));
}

void test_10_is_factor_of_10()
{
    assert(is_factor(10, 10));
}

void test_3_is_not_factor_of_10()
{
    assert(!is_factor(3, 10));
}

void test_aliquot_sum_of_6()
{
    assert(6 == aliquot_sum(6));
}

void test_aliquot_sum_of_28()
{
    int sum = 1 + 28 + 2 + 14 + 4 + 7 - 28;
    assert(sum == aliquot_sum(28));
}

void test_aliquot_sum_of_negative()
{
    assert(0 == aliquot_sum(-20));
}

void test_aliquot_sum_of_max_int()
{
    assert(1 == aliquot_sum(2147483647));
}

void test_the_first_five_perfect()
{
    assert(is_perfect(6));
    assert(is_perfect(28));
    assert(is_perfect(496));
    assert(is_perfect(8128));
    assert(is_perfect(33550336));
}

static const int PERFECT_NUMS[] = {6, 28, 496, 8128, 33550336};
bool find_num_in(int num, const int *perfects, int size)
{
    bool found = false;
    int i = 0;
    while (!found && i < size)
    {
        if (perfects[i++] == num)
        {
            found = true;
        }
    }
    return found;
}

void test_non_perfect()
{
    int size = sizeof(PERFECT_NUMS) / sizeof(int);
    for (int i = 2; i < 10000; i++)
    {
        if (find_num_in(i, PERFECT_NUMS, size))
        {
            assert(is_perfect(i));
        }
        else
        {
            assert(!is_perfect(i));
        }
    }
}

int main()
{
    test_1_is_factor_of_10();
    test_10_is_factor_of_10();
    test_3_is_not_factor_of_10();
    
    test_aliquot_sum_of_6();
    test_aliquot_sum_of_28();
    test_aliquot_sum_of_negative();
    test_aliquot_sum_of_max_int();
    
    test_the_first_five_perfect();
    test_non_perfect();
    
    return 0;
}