1.0.1 • Public • Published


a simple, tap-compliant test runner for the browser


  • importable as type="module"
  • is interoperable with TAP Version 14
  • nested sub-tests run in an iframe
  • has a recognizable testing interface (it, describe, assert)
  • can be used for automated testing
  • can be used to assert coverage goals



The following are exposed in the testing interface:

  • test: Creates a sub-test in an iframe based on given src html page.
  • it: The smallest testing unit — can be asynchronous.
  • it.skip: An it whose callback is not run and which will pass.
  • it.only: Skip all other it tests.
  • it.todo: An it whose callback is run and is expected to fail.
  • describe: Simple grouping functionality.
  • describe.skip: Skip all it tests in this group.
  • describe.only: Skip all other describe groups and it tests.
  • describe.todo: Mark all it tests within this group as todo.
  • waitFor: Ensures test registration remains open until given promise settles.
  • assert: Simple assertion call that throws if the boolean input is false-y.
  • coverage: Sets a coverage goal for the given href.


  • x-test-client-ping: root responds (x-test-root-pong, { status: 'started'|'ended' waiting: true|false })
  • x-test-root-pong: response to x-test-client-ping
  • x-test-root-coverage-request: client should respond (x-test-coverage-result)
  • x-test-client-coverage-result: response to x-test-root-coverage-request
  • x-test-root-end: all tests have completed or we bailed out
  • (internal) x-test-root-run: all tests have completed or we bailed out
  • (internal) x-test-suite-coverage: signal to test for coverage on a particular file
  • (internal) x-test-suite-register: registers a new test / describe / it
  • (internal) x-test-suite-ready: signal that test suite is done with registration
  • (internal) x-test-suite-result: marks end of "it" test
  • (internal) x-test-suite-bail: signal to quit test early


The following parameters can be passed in via query params on the url:

  • x-test-no-reporter: turns off custom reporting tool ui
  • x-test-run-coverage: turns on coverage reporting**

**See test.js for an example of how to capture coverage information in puppeteer and send it to your test to allow your automated test to fail due to unmet coverage goals.


Both test and it calls will execute in order**. test calls will boot the given html page in an iframe. Such iframes are run one-at-a-time. All invoked it calls await the completion of previously-invoked it calls.

**This is not the case if you nest it--but that's an anti-pattern anyhow.

Usage with puppeteer

See test.js for an example of how you can use puppeteer to run your app's tests and log the resulting TAP output to the console.

Parsing TAP

There are many TAP formatters. Importantly, as long as you can pipe the TAP output to another program, the output should be interoperable.




Package Sidebar


npm i @netflix/x-test

Weekly Downloads






Unpacked Size

121 kB

Total Files


Last publish


  • kkwon
  • kaylie
  • donutespresso
  • tbranyen
  • tvui-user
  • tvuiops-user
  • gsimpson
  • barb_the_builder
  • mmarchini
  • wesleytodd