Cat-herd's Crook: Enforcing Standards in 10 Programming Languages

At MongoDB we write open source database drivers in ten programming languages. Ideally, all behave the same. We also help developers in the MongoDB community replicate our libraries’ behavior in even more (and more exotic) languages. How can we herd these cats along the same track? For years we failed, but we’ve recently gained momentum on standardizing our libraries. Testable, machine-readable specs prove which code conforms and which does not.