Yes. This threw me off for a good while thinking that grid renderer wasn't working right. As it turns out test.py only renders the first layer defined in the style when running the test for grid renderer. I found other examples of tests that contain multiple layers and have expected output which only includes the first one. I'm not sure if the grid is only intended to be used for one layer at a time, or if there was some other reason for this. It does make testing all the behaviors in grid renderer specifically more difficult though.