If you were to ask “What are the most difficult aspects of testing a game engine,” an answer you’d hear a lot is “rendering.” What things look like when they’re drawn to screen–how do you test that? Well, to know that things drawn to screen look right you need to compare the rendered image to an image you can expect to be static, unchanging. The first approach is to create an image test fixture of the expected render image and compare that against the render image itself. However, this approach is extremely limited. As unfortunate as is is, we must leave the domain of simple static tests, and enter into the wacky world of dynamically testing.