1.4.0 • Public • Published

Tap Monkey


Screencast of Tap Monkey in action. Terminal window. Command: npm -s test. Progress of tests being run is shown by a single-line animation of the emoji monkey heads alternating between see no evil, hear no evil, speak no evil poses as the titles of test collections being run and passing tests are shown alongside. At the end, an emoji banana is shown next to “All tests passing. Total: 163. Passing 163. Failing 0. Duration 14.19 secs.

A tap formatter that’s also a monkey.

Displays test runner status using a static single-line spinner (hint: it’s a monkey) and only fills your screen with text on failures and with your coverage report.

Use it like tap-spec for running regular tests and also like tap-nyc for running coverage with c8 or nyc.


npm i @small-tech/tap-monkey


Pipe your tap test output to tap-monkey (e.g., if your test.js file contains tape tests):

node test.js | npx tap-monkey

Or, as a test task in your package.json file:

"scripts" : {
  "test": "node test.js | tap-monkey"

Or, if you have more than one test file:

"scripts" : {
  "test": "tape test/**/*js | tap-monkey"


For a quieter monkey, use the --quiet flag. e.g.,

"scripts" : {
  "test": "tape test/**/*js | tap-monkey --quiet"

When this flag is passed, only an initial notice is shown that tests are running and no further updates are given unless there are failures or until the final summary and/or coverage report are shown.

This is a general accessibility and usability feature. It might help folks using assistive devices like screen readers who might otherwise get overwhelmed by notifications of running/passing tests as well as anyone else who wants a generally calmer monkey.

Code coverage

Screenshot of Tap Monkey running coverage with a lovely coverage report surrounded by a single-line border with rounded corners drawn using box drawing characters.

Use Tap Monkey for code coverage in exactly the same way as you do for your tests.

e.g., using c8:

"scripts" : {
  "coverage": "c8 tape test/**/*js | tap-monkey"

Test failures

Screenshot of Tap Monkey showing a failed test. Full test details, including a stack trace are shown. At the end are the aggregate statistics.

While passing tests are displayed ephemerally in the status line so as not to fill up your terminal window with unnecessary information, failed tests are always written in full to the terminal.

(When running tests, we don’t care about passing tests, only failing ones.)

Debug output

Any console output that is generated by your program (e.g., from console.log() statements) is displayed in full and separate from the current test status line.

This is useful while debugging. (I like to have regular and debug test tasks in my code and use the latter when debugging an issue encountered in a test.)

e.g., my regular tests define an environment variable that silences console output but I have a separate debug test task that doesn’t include this.

"scripts" : {
  "test": "QUIET=true tape test/**/*js | tap-monkey",
  "test-debug": "tape test/**/*js | tap-monkey"

Then, all you need is to use a conditional log function in your app that checks for that environment variable. e.g.,

// Conditionally log to console.
export default function log (...args) {
  if (process.env.QUIET) {

Error behaviour

If your test runner (e.g., ESM Tape Runner) encounters an error in your app’s source code (e.g., a syntax error in one of your classes), it should bail out (and hopefully also log the error so you know what it is). Tap Monkey will respond to bail out events by displaying them and exiting (your test runner should have exit also so you should not get any pipe errors).

Testing Tap Monkey

Tap Monkey itself, of course, comes with unit tests displayed by none other than *drumroll* Tap Monkey!

Run tests

npm run -s test

Run coverage

npm run -s coverage

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© 2021 Aral Balkan, Small Technology Foundation.



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