The “exotic” types of testing that interest me here (fuzz testing, generative testing, property-based testing, metamorphic testing and mutation testing) are not talked about much in the JS community. I believe that is not because they are known to be unhelpful, but rather because little is known about them at all. Libraries to enable these sorts of testing are still immature, but now reaching a point where it is possible for developers to try them out and come to their own opinions …