I am working on an API that in wraps C++ behaviors with C calling convention functions. The API is composed of a collection of shared libraries (dll) that may be used in a variety of languages. In instances where a C++ class object is pass across the dll boundary, a C opaque pointer or "Handle" is used to refer to the underlying C++ object, similar to the Win32 API. An example header file prototype of such a wrapper function is
extern "C" { __declspec(dllexport) int __cdecl MyObjConfig(MyObj_t* handle); }
Many of the API functions / classes interface with hardware peripherals. In many cases it's not practical to be able to test on the representative hardware system. I would like to find a way to mock the lower level components so that higher level libraries or exectuables using those libraries can be tested in a simulated environment. However, I'm loathe to include phrases in the underlying source code such as
if(is_test) { return 0; }
For example, I would like to mock the behavior of a function float GetSensorData() so that I can test an executable that links to GetSensorData's parent dll and calls get sensor data, by returning a reasonable imitation of the sensor's normal data, without setting up the sensor explicitly. Also, I would like to avoid having to alter the source of the executable beyond making sure it is linking to an imitation of GetSensorData's dll.
A key part of my interest in an automated framework for creating the dll mocks is that I don't want to have to maintain two seperate versions of each library: a test version and an actual version. Rather I would like to work on the actual and have the "mock" compilation generated programmatically.
Can anyone suggest a good way to do this? I've looked at Gtest and CMock / Unity. Both seem fine for testing the dlls themselves but don't seem well equipped to accomodate the
extern "C" { __declspec(dllexport) int __cdecl
function prototype declarations.
Thanks!
