Test harness that emits the Test Anything Protocol (TAP).

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Test harness that emits the Test Anything Protocol (TAP). It runs in Node.js and web browsers, and is written in literate Parenscript (Common Lisp).
$ npm install tapdance


When the test exits, Tapdance will return a 0 exit code if nothing went wrong, and a non-zero exit code otherwise. There is no need to manually call when a test ends.


Run a function which may return a Promise. Calls to runTest get collected synchronously and run in sequential order in the next tick, which is useful when splitting up asynchronous tests in different files. The fn accepts two arguments, assert and comment.

assert(value, message)

Check if a value is truthy or not.


Output a comment line.


This can be overridden to use a different assert function.


You will need a Common Lisp implementation like SBCL, and wget. If installing the developer dependencies didn't work the first time, you may need to cd node_modules/sigil-cli && make.


This software is licensed under the MIT License.


Here's the full source code.
"use strict"
(defvar *assert* (require "assert"))
Check if it's running in Node.js, this determines whether or not to call Node.js specific APIs.
(defvar *is-node*
 (and (not (eq (typeof process) 'undefined))
      (eq (typeof (@ process exit)) 'function)
      (eq (typeof (@ process next-tick)) 'function)))
Initialize the local state of the program which is read & written later.
(defvar *start-time* ((@ *date now)))
(defvar *stack* (array))
(defvar *count* 0)
(defvar *passing* 0)
A bit a ceremony is needed to kick off the TAP output. This kicks off the running of tests.
(println "TAP version 13")
(if *is-node*
    (progn ((@ process on) 'exit exit)
           ((@ process next-tick) flush))
  (set-timeout flush 0))
Define the main public function, it accepts a test function that takes two arguments, assert and comment.
(setf (@ module exports) run-test)
(setf (@ run-test assert) *assert*)
(defun run-test (fn)
  (defun assert (exp message)
    (incf *count*)
      (progn ((@ run-test assert) exp)
             (incf *passing*)
             (println (+ "ok " *count* " " message)))
      (:catch (error)
        (println (+ "not ok " *count* " " message))
        (show-error error))))
  (defun comment (message) (println (+ "# " message)))
  ((@ *stack* push) (lambda () (fn assert comment))))
This is an implementation detail which runs all of the testing functions in the order that they are declared.
(defun flush ()
  ((@ ((@ *stack* reduce)
       (lambda (chain fn)
         ((@ ((@ chain then) fn) catch)
          (lambda (error)
              (incf *count*)
              (println (+ "not ok " *count* " " (@ error message)))
              (show-error error)))))
       ((@ *promise resolve))) then)
   (lambda () (if *is-node* ((@ process exit)) (exit)))))
Upon exiting, print the results as well as some useful information such as how many tests failed and how long it took.
(defun exit ()
  (if *is-node*
      (setf (@ process exit-code)
            (if (and *count* (eq *count* *passing*)) 0 1)))
  (if (not *count*)
      (progn (incf *count*) (println "not ok 1 no tests found")))
  (println (+ "1.." *count*))
  (if (eq *count* *passing*)
      (println "# all tests passed")
    (let ((failing (- *count* *passing*)))
       (+ "# " failing " test" (if (> failing 1) "s" "") " failed"))))
   (+ "# test finished in " (- ((@ *date now)) *start-time*) " ms"))
Internal function to pretty print errors that happen while running tests.
(defun show-error (error)
  (println "  ---")
  (println (+ "  name: " (@ error name)))
  (if ((@ (regex "\\n") test) (@ error message))
        (println "  message:")
        ((@ ((@ error message split) #\linefeed) map)
         (lambda (line)
           (println (+ "    - " line)))))
      (println (+ "  message: " (@ error message)))
      (if (@ error stack)
            (println "  stack:")
            ((@ ((@ error stack split) #\linefeed) for-each)
             (lambda (line)
               (setf line ((@ line trim)))
               (if (not (eq ((@ line index-of) (@ error name)) 0))
                   (println (+ "    - " line)))))))))
  (println "  ..."))
Internal function to print lines while escaping new lines in the input.
(defun println (str)
  ((@ console log)
   (if str ((@ str replace) #\linefeed "") "")))