Ahhh I've made this mistake before. You can't test every input/output while also losing the ability to accurately depict stateful user flows. Even Fintech proje

Ahhh I've made this mistake before. You can't test every input/output while also losing the ability to accurately depict stateful user flows. Even Fintech projects I've worked on at the >£10Bn daily volume mark combining formal methods, mathematical proofs, property based tests, fuzzing, model based testing, etc.. still caught issues pre-production via good old end-to-end tests. Good luck nubank :)