junit-quickcheck VS rs-lox

For anyone interested, there's also https://github.com/pholser/junit-quickcheck . Haven't used it myself but looks like an interesting library to explore. It's based on QuickCheck as well AFAIK.

Thank you for the insightful reply. I did struggle to convert the original algorithm I wrote (with while loops / continue / break) to a more functional style using unfold, and also faced an issue with the type signatures when I tried to break down the contents of Stream.unfoldRight to multiple functions, which is reflected to the messy state you mentioned. Regarding property based testing, I used junit-quickcheck and the "symmetry" property check was one I meant to write but wasn't quite sure how to create a generator for it. I created an issue to track my attempt to incorporate your suggestions in case you are interested in following this. Thanks again!

A quick Google search shows that java has a library for this (here) but I've never used it in java so can't attest to it.

QuickcCheck-type tools (generators for tests that know about the edge cases of a domain - e. g. for the domain of numbers considering things like 0, the infinities, various almost-and-just-over powers of two, NaN and mantissas for floats, etc.):

* QuickCheck: https://hackage.haskell.org/package/QuickCheck

* Hypothesis: https://hypothesis.readthedocs.io/en/latest/

* JUnit QuickCheck: https://github.com/pholser/junit-quickcheck

Fuzz testing tools (tools which mutate the inputs to a program in order to find interesting / failing states in that program). Generally paired with code coverage:

* American Fuzzy Lop (AFL): https://github.com/google/AFL

* JQF: https://github.com/rohanpadhye/JQF

Mutation / Fault based test tools (review your existing unit coverage and try to introduce changes to your _production_ code that none of your tests catch)

* PITest: https://pitest.org/

If you want an easy way to have better mutation coverage, check out property based testing. Eg junit-quickcheck for Java.

https://github.com/pholser/junit-quickcheck

On my current pet project, it has written almost all of the tests here: https://github.com/golergka/rs-lox/blob/master/src/compiler.... ad here: https://github.com/golergka/rs-lox/blob/master/src/scanner.r... (albeit not the screwed indentation) completely by itself. I didn't even have to write the function names, just a few macros to help it along and a couple of examples to teach it to use it.