Learn about our RFC process, Open RFC meetings & more.Join in the discussion! »


2.3.13 • Public • Published

npm version License GitHub

GitHub Workflow Status (branch) Codecov

GitHub Workflow Status (branch) Codecov



just-test is a browser oriented tests runner strongly oriented to a TDD of a client side libraries, frameworks and components.

Why would we have another one? just-test is strongly oriented to dev real time process. It has actually began as a code running playground during my next framework development and from there evolved to be a tests runner.

The main point is to provide a shortest path for a developer to execute newly written code in the browser, re-run it while benefitting from the browser's debug tools, fix the source and re-test the whole again just in a click of refresh.

just-test became to myself a truly TDD enabler as I'm using it in over a few dozens of libraries as of now. While being perfect tool for a librarires/components development, I'm still looking to see is and how could it be used to test a full web application.


  • running tests in browser, no server needed, import/link your code (static files) and just test, literally TDD oriented
  • re-running any test in browser ad-hoc - convenient for debugging and developing on the fly
  • friendly UI on top of the page of the tests, allows immediatelly observe the behavior of the code and the test
  • running tests from NodeJS via headless browser (currently: Chromium) to run in CI/CD automation
  • generating test results report (format: xUnit)
  • collecting coverage and generating report (formats: lcov)
  • flexible yet simple ability to run tests in sync as well as async (default) manner
  • in general, a lot of attention was paid to create simple and usable framework even for a not-so-simple cases, like asynchronous tests etc

Attention: the doc below is still in construction, more updates and detailed one will be published very soon!!! Meanwhile, the best way to actually see how the library should be used is it look onto its own tests in tests folder, and for CI/CD case - travis.yml is a good start.

How it works - dev process

  • start from writing a first lines of your next component or framework
  • create a test file, test.js for example
  • import into it the just-test APIs and get the suite object by the getSuite API
  • import the stuff your are working on and write some testing code using suite's runTest API
  • create an empty html file, test.html for example
  • import test.js into it and open it in browser

Congratulations! Your test/s are running. You see the results organized in suites in the just-test UI. You may re-run any test from the UI, see the errors if any, status, duration etc.

CI readiness

just-test is not only a convenient work frame to develop and test the code at once, but also a CI automation ready tool. Provided additional configuration file (full example may be seen here) just-test is able to:

  • run your tests in CI in the following browsers: Chrome, Firefox (experimental); Edge Chromium will be added as soon as puppeteer platform will handle the download of the Edge's executable
  • creates report in the following formats: xUnit
  • creates coverage report in the following formats: lcov


Typical usage of the JustTest would involve two steps:
(A) referring to the framework and the tests in your html page;
(B) writing the actual test logic using an API (look example below and APIs).


    <script src="just-test.js"></script>
    <script src="test1.js"></script>
    <script src="test2.js"></script>


(function() {
    'use strict';

    var JT = window.Utils.JustTest, suite;

    suite = JT.createSuite({ name: 'Suite object APIs' });

    suite.addTest({						//	options list described in API section below
        name: 'JustTest namespace created okay'
    }, function (pass, fail) {
        if ('your internal validation logic fails') fail(new Error('error notice'));
        if ('another fail') throw new Error('calling "fail" and throwing have the same effect');


(function() {
    'use strict';

    var JT = window.Utils.JustTest, suite;
    suite = JT.createSuite();

    suite.addTest(function (pass, fail) {		//	can skip the options, defaults will be used


Framework object (default window.Utils.JustTest):

Test (JustTest.Test):

Suite (JustTest.Suite):


npm i just-test

DownloadsWeekly Downloads






Unpacked Size

113 kB

Total Files


Last publish


  • avatar