The Common Lisp Cookbook – Testing

So you want to easily test the code you’re writing? The following recipes cover how to write automated tests. We will use an established and well-designed regression testing framework called Prove. It is not the only possibility though, FiveAM is a popular one. We prefer Prove for its doc and its extensible reporters (it has different report styles and we can extend them).


Prove is in Quicklisp:

(ql:quickload :prove)

This command installs prove if necessary, and loads it.

Write a test file

(in-package :cl-user)
(defpackage my-test
  (:use :cl
(in-package :my-test)

(subtest "Showing off Prove"
  (ok (not (find 4 '(1 2 3))))
  (is 4 4)
  (isnt 1 #\1))

Prove’s API contains the following testing functions: ok, is, isnt, is-values, is-type, like (for regexps), is-print (checks the standard output), is-error, is-expand, pass, fail, skip, subtest.

Run a test file

(prove:run #P"myapp/tests/my-test.lisp")
(prove:run #P"myapp/tests/my-test.lisp" :reporter :list)

We get an output like:


Prove can also:

  • be run on Travis CI,
  • colorize the output,
  • report tests duration,
  • change the default test function,
  • set a treshold for slow tests,
  • invoke the CL debugger whenever getting an error during running tests,
  • integrate with ASDF so than we can execute (asdf:test-system) or (prove:run) in the REPL (such configuration is provided by cl-project, by the same author).

See Prove’s documentation !