test.c

// when depoyment
//
// $ gcc sample.c main.c -o sample

// when testing
//
// $ gcc -DDEBUG sample.c test/test_main.c -o test/test
#include <stdio.h>

#define FAIL 1
#define SUCCESS 0

static int
f()
{
    return 1;
}

#ifdef DEBUG
int f_test()
{
    if(f() != 1)
    {
        printf("fail\n");
        return FAIL;
    }
    return SUCCESS;

}
#endif