[michaelmcmillan]

As someone who always writes unit tests before any production code, I don't know how I would have the time to not write tests. It drives the design and reduces time debugging by a ridiculous amount. I work with information systems though, might be different for other fields.

[lmm]

Since I've switched to a language with a richer type system (Scala) I've found a lot of what I used to do with unit tests can go into the type level instead (see e.g. http://spin.atomicobject.com/2014/12/09/typed-language-tdd-p... - but in Scala the techniques are a lot less verbose to apply).

[michaelmcmillan]

I am most familiar with Javascript & Python, but I think you're onto something having fiddled with Java for 6 months or so. Some logic obviously can't be replaced with only a rich type system, but a lot can.