The Ruby community has a very good culture of testing application and framework code, but in my experience is quite poor at properly specifying behaviour or wri

The Ruby community has a very good culture of testing application and framework code, but in my experience is quite poor at properly specifying behaviour or writing truly robust code. Many functions in the standard library behave subtly differently from there documentation or have behaviour that is not documented but depended on by applications, and I’ve certainly seen lots of concurrency bugs in both code and tests because the GVL makes it hard to provoke the worst case behaviour. The unit tests are really useful for Ruby language implementations because they help give us confidence we’re replicating all the required behaviour, but from that point of view I wish the underlying things were better specified so those tests weren’t quite so necessary. Don’t get me wrong. I love Ruby as a language and loved working on TruffleRuby, but I don’t think the community should be too smug about code quality and testing.