Using devcards for testing a ClojureScript Chrome extension


A few weeks ago I wrote a short piece about the available tools for building Chrome extensions in ClojureScript.

Among the tools I reviewed was khroma, a still very much work-in-progress ClojureScript library providing idiomatic access for the Chrome API. One of original comments I had was that khroma was still incomplete, and had some not entirely evident function names.

I have since taken up khroma development and begun extending and refactoring it. However, a question immediately came up: how do we go about testing it? Your first impulse might be to say “why, don’t we have cljs.test?”.

Yes, we do, but we can’t run these tests automatically from the command line: the APIs are only available when you’re running inside Chrome as an extension with the right permissions.

Moreover, I’d like to be able to provide usage samples and data review for the myriad of events you can hook up to, some of which aren’t easily testable because they depend on user input, or asynchronous inter-page communication. How to go about this, then?

Enter devcards.