PS: Using the latest Xcode versions, all tests now fail with: Test crashed with signal ill.

Ok, I was able to further dive down on the issue: let device = MTLCreateSystemDefaultDevice() seems to not be available. We use several Metal compute shaders in our code and tests. I shouldn't have force-unwrapped the MTLCreateSystemDefaultDevice and fixed that, but we do need a device to test the functions that rely on the device..