This section explains the process of working with CIDER's codebase (e.g. to fix a bug or implement some new feature). It outlines the recommended workflows when working on the Emacs Lisp side (CIDER) and the Clojure side (cider-nrepl).

Hacking on CIDER

Obtaining the source code

People typically install CIDER via package.el. While this gives you access the source code (as it's part of the package), it's always a much better idea to simply clone the code from GitHub and use it. In general - avoid editing the code of an installed package.

Alternatively you can simply load CIDER in your Emacs straight from its source repo:

;; load CIDER from its source code
(add-to-list 'load-path "~/projects/cider")
(require 'cider)

Just keep in mind that you'll have to manually install all the packages CIDER depends on in advance.

Changing the code

It's perfectly fine to load CIDER from package.el and then to start making experiments by changing existing code and adding new code.

A very good workflow is to just open the source code you've cloned and start evaluating the code you've altered/added with commands like C-M-x, eval-buffer and so on.

Once you've evaluated the new code, you can invoke some interactive command that uses it internally or open a Emacs Lisp REPL and experiment with it there. You can open an Emacs Lisp REPL with M-x ielm.

You can also quickly evaluate some Emacs Lisp code in the minibuffer with M-:.

Testing the code

The code you've wrote should ideally be covered by specs. We use the buttercup library for CIDER's specs. If you're familiar with Jasmine or RSpec you'll feel right at home.

You can run the specs you authored/changed straight from Emacs. Consult the buttercup documentation for all the details.

Running the tests in batch mode

If you prefer running all tests outside Emacs that's also an option.

Install cask if you haven't already, then:

$ cd /path/to/cider
$ cask

Run all tests with:

$ make test

(Note: tests may not run correctly inside Emacs' shell-mode buffers. Running them in a terminal is recommended.)

You can also check for the presence of byte-compilation warnings in batch mode:

$ make test-bytecomp

Hacking on cider-nrepl

Obtaining the code

Just clone it from GitHub.

Changing the code

Just do cider-jack-in within the cider-nrepl project and start hacking as you would on any other Clojure project. The only thing to keep in mind is that you'll have to restart CIDER when you add new middleware.

The jacked-in project's definitions will take precedence over the once you have from a binary cider-nrepl installation. This means it's pretty easy to get immediate feedback for the changes you've made.

Testing the code

The code you've wrote should ideally be covered by test. We use the clojure.test library for cider-nrepl's tests.

You can run the tests you authored/changed straight from Emacs. Consult the CIDER documentation for all the details.

Running the tests in batch mode

You can also run the tests in an external shell. Running lein test won't run pretty much anything, though. (perhaps we should change this?) To run the Clojure and ClojureScript tests you should specify some profile like this:

$ lein with-profile +1.8,+test-clj test"
$ lein with-profile +1.8,+test-cljs test"

This will run all Clojure and ClojureScript tests against version 1.8 of both languages.