I think setting the expectation .withOutputParameterReturning() should copied the value pointed to. However, it stores the pointer and dereferences it on the actualCall().withOutputParameter().

If the call .withOutputParameterReturning() copies the given memory it would allow the memory to be changed between expect and actual calls.

The problem was encountered when trying to mock an interface where the .withOutputParameterReturning() is given a chunk of dynamically allocated memory which is free'd (and reused) before the actual call.

This is the simplest example I can come up with to reproduce the issue.

TEST(MockParameterTest, outputParameterReturningShouldCopyOnExpect)
{
    int param = 1;
    int retval = 2;

    mock().expectOneCall("function").withOutputParameterReturning("parameterName", &retval, sizeof(retval));
    retval = 7; 

    mock().actualCall("function").withOutputParameter("parameterName", &param);
    CHECK_EQUAL(param, 2); // Check fails !!!

    mock().checkExpectations();
}