Additionally, if you're using tape[1] for testing, I implemented a useful feature not too long ago to allow the preloading of modules[2] so you can run something like babel-register before your tests are run, effectively plugging in JIT-like support for your tests. (End shameless plug.)

[1]: https://github.com/substack/tape

[2]: https://github.com/substack/tape#preloading-modules