Testable C application using posix threads

Question

I have to write code that would look do something like that (of course much more complicated):

int stop;
int isStopped;

void workerFunction(){
    while(!stop){
        //...
    }
    isStopeed = 1;
}

startThread(){
    int newThreadPid = pthread_create(..., NULL, workerFunction, NULL);
}

stopThread(){
    stop = 1;
}

My question is: are there any techniques that can make such code testable? I don't think writing tests like :

startThread();
stopThread();
sleep(1);
ASSERT(isStopped);

is the best idea. How to test stopThread() function without calling system function? Is there any way to mock pthread_create?

Answer 1

I only know one way to mock functions in C: Have function pointers to mockable functions and only ever call them through that pointers. For your tests you would adjust the pointers to point to your mock functions instead. But I don't know if you really want to go down that route....