how to return the error code when mocking a recvmsg function?

Question

I am using google test and google mock to test some C code:

struct msghdr message;
int retval;

retval = recvmsg(fd,&message,0);

if(retval == EINTR || retval == EAGAIN)
{
    // do something here
}

in my mock file, I mocked the recvmsg function:

MOCK_CONST_METHOD3(recvmsg, int(int fd, struct msghdr *msg, int flags));

but how to set the errno as EINTR or EAGAIN when I set the return value of the mock function recvmsg as -1?

Answer 1

Google Mock docs 中有一个名为SetErrnoAndReturn(errnum, value)的标准操作。

Answer 2

You cannot mock free functions, but only class virtual member functions.

The proposed solution to mock free functions in the docs is to define an interface exporting a virtual member function with the same signature as the free function. Then define an implementation that wraps up the call to the free function for production code and a mock for testing. So if your testing code is pure C, it won't be a solution for you.