A mocking framework

mock.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <ctype.h>

void mock(char* s) {
    srand(time(NULL));

    for (int i = 0; s[i]; i++) {
        if (rand() % 2 == 0)
            s[i] = toupper(s[i]);
        else
            s[i] = tolower(s[i]);
    }
}

int main() {
    char str[] = "this is the mock string";
    mock(str);
    printf("%s\n", str);
}