And push the boundaries out as far as you can
I will motivate why you should always define the boundaries of your system as small and as far out as possible and why you should only test them, instead of the rest of your system.
Domain driven design is as old as some programmer's beards, yet recently it gained some unexpected attention. And hate. I explain my perspective and how we can stay healthy with that topic.
Testcontainers and repository abstraction in combination with a good testing framework like JUnit can be so nice.
Now with better surface normals, lighting and environment maps. Video inside.
Some bad habits have been established, some myths can be falsified about testing with filesystems.
Unit tests are outdated. Developer tests replace them.
Persistent buffers and manual synchronization can be used to asynchronously upload texture data without doing expensive calls to the graphics api.