doctest/examples/installed_doctest_cmake/dll/dll.cpp

#define DOCTEST_CONFIG_IMPLEMENTATION_IN_DLL
#define DOCTEST_CONFIG_IMPLEMENT
#include <doctest/doctest.h>

#include "dll.h"
#include <stdio.h>

extern "C" {
    void say_hello_dll() { printf("%s", "Hello, World!\n"); }
}

int factorial(int number) {
    return number < 1 ? 1 : number <= 1 ? number : factorial(number - 1) * number;
}

TEST_CASE("testing the factorial function") {
    CHECK(factorial(0) == 1);
    CHECK(factorial(1) == 1);
    CHECK(factorial(2) == 2);
    CHECK(factorial(3) == 6);
    CHECK(factorial(10) == 3628800);
}