我在主cpp中多次使用了一些外部依赖函数，我试图为单元测试准备代码，所以我想用模拟实现来替换外部依赖，我将如何在主cpp文件中将那些转换为模拟实现？

//ExternalDependencies.hpp
#include <cstdint>
#include <set>
#include <unordered_set>

namespace lab04{
namespace task_common{
namespace project{

uint32_t lab04::task_common::project::CalculateID(const uint32_t id)
{
    constexpr uint32_t temp= 0xFFF0;
    return id& temp;
}

inline StreamType lab04::task_common::project::GetType(const uint32_t width) 
{
    switch (width)
    {
        case 1:
            Type = Type::Short;
            break;
        case 0:
            Type = Type::Long;
            break;
        default:
            THROW(ConfigErr, "Eror!");
    }
    return Type;
}

uint32_t lab04::task_common::project::CalculateBS(const uint32_t Count, const uint32_t Size)
{
    return ((Count + 146) *(Size * 1676));
}

} 
}
}