I'd go the other way - rather than generate code from templates, declare the dynamic parts of the page in code, and generate both the implementation and the test accessors from that (I'd use a Wicket-like approach where the HTML fragments only included ids and all the logic was in code). I haven't seen this done for the actual HTML side of things, but https://github.com/http4s/rho gives you a declarative way to, uh, declare your HTTP routes, and then you can generate swagger or a client from the exact same declarative routing construct value that you're using to run your actual routes.