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Guided by the beauty of our test suite

This is a story about making software better. Last summer, I published Raven, an independent implementation of the Uxn CPU and Varavara ordinator.

I had previously done ad-hoc testing while deeply immersed in the system; coming back months later, it was hard to touch the code and remain confident that I hadn't introduced any new issues. I added automatic tests which run the system for some number of cycles, then capture the state of the screen and compare it with a known-good image saved in the repository. Sufficiently advanced fuzzing libraries will actually monitor the code paths (using debugging infrastructure), and are smart about mutating the input to fully explore the program's state space.

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