It doesn't look like there are many unit tests for D3D in general, but D3D8 and WineD3D don't seem to have any. The ones that D3D9 has also don't test the generated graphics for conformance.
Would it be a viable/appropriate SOC project to put together a test suite for D3D, including graphical conformance tests? I should probably note that I have no experience using DirectX and minimal experience using OpenGL. Still, a whole summer should be enough time to put together a reasonably comprehensive test suite (perhaps excluding shaders).
Thanks, Sagar Mittal