figwheel-main is a re-write of Figwheel, that doesn’t depend on lein-cljsbuild config and doesn’t require Leiningen at all. Migrating a Leiningen project to it is not too difficult but there may be a few gotchas, depending on your project, as figwheel-main doesn’t support all of the config options of lein-figwheel. Also, our specific case was to continue using Cursive nREPL integration - something we were enjoying with lein-figwheel.

Testing

The nice thing about new Figwheel is that it includes a dedicated test runner so we were able to remove our devcards setup which we copied from 8th Light blog. Now the tests can be executed simply by navigating to localhost:9500/figwheel-extra-main/auto-testing when Figwheel is running, provided that:

• the "test" directory is included in :watch-dirs
• :auto-testing is set to true

Both the :watch-dirs and :auto-testing are Figwheel config options, which we store in dev.cljs.edn file as a metadata map of a compiler config map. We moved the compiler config map itself from :cljsbuild :dev config in project.clj - more on it in the section below.

While devcards is useful for many things, and we enjoyed using it for running unit tests, there were a few gotchas in this use case. The main was that each namespace would have a separate ‘page’ so running all tests in a project at once was not obviously possible.

No :cljsbuild config

As already mentioned, unless you have a specific need for it, most or all of :cljsbuild config maps, and the lein-cljsbuild plugin itself, can be removed from project.clj, because Fighweel is now able to do a minified build as well. Our config for it is in min.cljs.edn file which contains the same map as the :compiler map in now-removed :cljsbuild :min config. To run the build, type the following command, assuming you are using Leiningen:

lein trampoline run -m figwheel.main -bo min

binaryage/devtools included

This essential tool is now automatically included in dev Figwheel builds so the project dependency and the :preloads entry can be removed.

REPL

To get Cursive ǹREPL integration we did:

• replace any piggieback dependency with cider/piggieback
• add cider/cider-nrepl plugin

Also, this is how our :repl-options map looks like:

{:nrepl-middleware [cider.piggieback/wrap-cljs-repl]
 :init (do (require '[figwheel.main.api :as f])
           (future (f/start {:mode :serve} "dev")))
 :port 7890}

To run it, simply type:

lein repl

And then, after connecting your REPL to port 7890, just type this in the REPL:

(f/cljs-repl "dev")

This replaces the :nrepl-port option from lein-figwheel.

:on-jsload

The handly :on-jsload option, which specifies a function to call on each Figwheel refresh, is also gone. The replacement is easy though:

1. Add ^:figwheel-hooks metadata to the ns containing the function.
2. Add ^:after-load metadata to the function.

:open-urls

Also the :open-urls option is gone and replaced with :open-url which takes false or a string.

Summary

The summary is short. We are very happy with figwheel-main! Thank you, Bruce Hauman!