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pitesti is a tiny but useful test framework for Node.js. Node 12.x and higher are supported.

You can also use pitesti in browsers. See below for details.


  • Only output TAP.
  • Allow just about anything to be passed in as a "test". For example:
    • A function that either throws or doesn't.
    • A function taking a nodeback/errback, where the error indicates test fail.
    • A promise (whose result is assumed by the test).
    • A function returning a promise (whose result is assumed by the test).
  • Super-simple test definition format.
  • No setup or teardown functions (except in BDD mode).


First, create a test suite.

const test = require('pitesti')();

pitesti exports a single function which creates test suites. It takes in an options object (or nothing) with the following values:

  • outputStream: where to write TAP output. Default is process.stdout.
  • summary: whether or not to write a summary to the outputStream and the end of testing. Default is true.
  • timeout: Milliseconds after which to fail the test if it hasn't passed yet. Default is 5000. See "Timeouts" below.
  • contextSeparator: String used to separate context names from test names. Default is ' '.
  • done: a callback function that will take in an exit code. Default is process.exit.

Now you can write some tests and run them.

const test = require('pitesti')();

// any function returning a promise can be a test
test('foo example test 1', function(){
  return Promise.resolve();

// a failing test is one that returns a (eventually) rejecting promise
test('foo example test 2', function(){
  return Promise.reject(new Error('bad'));

// async functions also work just fine!
test('foo example test 3', async function(){
  await something();

// if you already have some promises lying around, you can pass those in
let myPromise = Promise.resolve();
test('foo example test 4', myPromise);

// you can call test as a template literal, for a fun DSL
test `foo example test 5` (() => Promise.resolve('good'));

// you can also have tests that just call a callback or throw
test `foo example test 6` (cb => {

// this starts running the suite

This will run the tests, outputting to the outputStream, and when done will call done, so in this example it will print the following to stdout and then exit.

TAP version 13
ok 1 foo example 1
not ok 2 foo example 2
  name: Error
  message: bad
  stack: |-
    Error: bad
      <stacktrace line 1>
      <stacktrace line 2>
      <stacktrace line 3>
ok 3 foo example 3
ok 3 foo example 4

Since one of the tests failed, the exit code is 1, rather than the 0 we'd get in a 100% success case.


You can use whatever assertion library you want, provided that you return a Promise whose end-result passes or fails the test, or just simply throw. Pretty much every assertion library falls under this, so you should be fine.

Skip and Only

You can skip or isolate a test the same way you would in Mocha. The template literal forms work as with just test.

test.only('only this test will run', function(){
    // ...
test.skip('all tests except this one will run', function(){
    // ...


By default, each test case has a time limit of 5000ms, after which the test will be considered a failure.

You can set a global timeout for an entire test suite using the options object as described above. You can also pass a third argument to the test function that is an options object containing a timeout option, in order to set a timeout for a specific test:

test('this is a test with a 1 second timeout', () => {
  // ...
}, { timeout: 1000 });

To completely disable timeouts, you can set a timeout property to Infinity.

Multiple Files

Pitesti isn't designed with files in mind. That means you're free to do whatever you want.

There are two main suggested approaches to take:

  1. Write test files as functions taking in the test suite function, and then pass that in to each module from a main test file.
  2. Use a tool like the node-tap cli to run all your test files as individual suites.

Grouping, Contexts

You can add a layer of context to tests by using test.context:

test.context('MyClass', () => {
  test('foo', () => { /* ... */ });
  test('bar', () => { /* ... */ });

You can do this up to an arbitrary depth.

You can change the separator used in the TAP output by using the contextSeparator option as defined above.

Mocha/BDD Syntax

A BDD-style interface is provided, exported as pitesti/bdd. The exported functions are as follows, with the effectively the same functionality as Mocha.

  • describe
  • context
  • it
  • before
  • beforeAll (same as before)
  • beforeEach
  • after
  • afterAll (same as after)
  • afterEach

If you'd like these as globals, you can do something like this.

Object.assign(global, require('pitesti/bdd'));

Note that Mocha's this object is not supported. Instead, to configure an individual test for timeouts, add an extra parameter to the it function, much like the test function in regular Pitesti.

For example:

it('does a thing', () => {
  // ... some slow code ...
}, { timeout: 10000 });

Much like with Mocha, you don't need to initiate the test suite. It will run on its own in a nextTick. Unlike Mocha, you cannot add additional test cases dynamically after the first tick.

NOTE: pitesti/bdd does not currently work in browsers.

Browser Usage

Pitesti can be used in a browser environment via webpack, browserify, or other web packaging tools.

You'll have to set an outputStream, so if you're using one of the tools above, you should be able to do something like:

const pitesti = require('pitesti');
const { Writable } = require('stream');
const out = document.getElementById('test-output');
const outputStream = new Writable({
  write(chunk, encoding, cb) {
    out.innerHTML += chunk;
const test = pitesti({ outputStream });


  • Pitesti runs tests sequentially. While running in "parallel" might sound better, in reality, many real-world tests involve singletons and other global state that's changed throught the course of a single test. It's far easier to reason about what's going on if only one test can be causing an error at any given time.
  • If your code fails to examine errors in errbacks/nodebacks, or does not handle promise rejections, you may find that these errors are invisible. The position taken by Pitesti is that if you're ignoring an error, you don't care that it's an error, and it's not a problem for your code.


Code licensed under MIT license. See LICENSE.txt