Hacking on CIDER
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 (
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 (you’ll have to manually install all the packages CIDER depends on in advance).
CIDER uses Eldev for development, so you should install the tool first.
The easiest and "purest" way to run CIDER is to execute:
This will start a separate Emacs process with CIDER and its
dependencies available, but without your normal packages installed.
However, you can use
Eldev-local to add some packages with
(eldev-add-extra-dependencies 'emacs …) forms. See Eldev
documentation for details.
Alternatively, if you want to load CIDER from source code in the Emacs you use for editing:
Generate autoloads file (that’s done automatically when installing via
package.elbut you’ll have to do it manually in this case):
eldev build :autoloads
Add to your
;; load CIDER from its source code (add-to-list 'load-path "~/projects/cider") (load "cider-autoloads" t t)
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
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
You can also quickly evaluate some Emacs Lisp code in the minibuffer with
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
RSpec you’ll feel right at
You can run the specs you authored/changed straight from Emacs. Consult the buttercup documentation for all the details.
If you prefer running all tests outside Emacs that’s also an option.
Run all tests with:
$ eldev test
Tests may not run correctly inside Emacs'
You can also check for compliance with a variety of coding standards in batch mode (including docstrings):
$ eldev lint
To check for byte-compilation warnings you can just compile the project with Eldev:
$ eldev compile
If you prefer to see the full CircleCI CI test suite run successfully, the easiest way to achieve that is to create your own personal account on https://circleci.com. Fork CIDER on GitHub, and then add your fork on CircleCI to start building. Every time you push code to a branch, CircleCI will build it.
Subsequent pushes to your fork will generate a CircleCI build you can monitor for success or failure.
If you prefer not to wait for CircleCI all the time, or if you need to debug something that fails in CircleCI but does not fail for you on your own machine, then you can also run the CircleCI tests locally with the CircleCI CLI (that’s a mouthful!).
Currently the CircleCI CLI doesn’t support local builds with version 2.1
of the CircleCI config, so for now we need to convert it to the 2.0 format.
Make sure not to commit these changes to the
$ circleci config process .circleci/config.yml > .circleci/config.yml.tmp && \ mv .circleci/config.yml.tmp .circleci/config.yml
Now, we’re finally ready to
run a CircleCI container on our machine.
circleci local execute --job=<job> where
<job> is one of those listed
$ circleci local execute --job=test-emacs-26 Docker image digest: sha256:65b2102646d5658f892e0ad8253b7912c676126c857c87c8c12460f0aa4f5aa1 ====>> Spin up Environment Build-agent version 1.0.8563-43047892 (2019-03-06T15:11:54+0000) Starting container silex/emacs:26-dev image cache not found on this host, downloading silex/emacs:26-dev 26-dev: Pulling from silex/emacs 6cf436f81810: Already exists 987088a85b96: Already exists e58f362a948a: Waiting ... ====>> make elpa #!/bin/bash -eo pipefail make elpa Compute dependencies cask install Loading package information... done Package operations: 10 installs, 0 removals ... Indenting region... Indenting region...done * Run indent-character * Run trailing-whitespace ** ELISP-LINT: cider-overlays.el OK Success!
This may take a while to download the CircleCI build agent and the build containers the first time you run the tests locally.
In general, CIDER code should work as well on Windows as it does on Unix.
There are a few points to be aware of when contributing code or writing tests.
Absolute paths. It is a common practice to use dummy absolute paths, such as
/docker/src, in tests,as test inputs. These are not valid absolute paths on Windows though, since they are missing the initial driver letter (e.g.
c:/tmp/a-dir), but we can wrap them around with
expand-file-nameto make them so e.g. in tests
(let a-dir (expand-file-name "/tmp/a-dir" (docker-src (expand-file-name "/docker/src"))) ;; … ) ---
Command-line arguments. When calling external programs, it might be necessary to quote some long command line arguments, though quoting rules are different on Windows (shells) that they are on Unix. Use
shell-quote-argumentto achieve the desired compatibility across the different architectures.
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.
The code you’ve wrote should ideally be covered by test. We use the
clojure.test library for
You can run the tests you authored/changed straight from Emacs. Consult the CIDER documentation for all the details.
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.