CLJS tests

[alex-dixon]

We've had a difficult time getting testing set up nicely in CLJS. Just opening this as an issue for now because it's an important one and should be tracked.

We might do well by looking at Clara's CLJS tests although they are in the process of refactoring them to CLJC. Helping them would help us. I'm also planning to create a PR to allow better REPL-driven CLJS test development modeled after the setup we have here which will provide an opportunity to learn their setup.