Thanks for the feedback. I am definitely a beginner in Haskell, which would explain why I came to this conclusion. Could you recommend some good sources on testing in Haskell?
While of course Haskell has more normal testing infrastructure available (eg. https://hspec.github.io/), my favorite bit of Haskell testing is QuickCheck, which IIUC started life in Haskell and has been reimplemented in other languages with various degrees of effectiveness and various degrees of connection to the original project.
John Hughes (not the filmmaker) gives a great talk about it: https://youtu.be/zi0rHwfiX1Q