Running Browser-Based CucumberJS Specs in Testling

2014 February 18th by todd anderson

In my previous posts I discuss bringing CucumberJS specs to the browser using the cucumberjs-browser CLI tool. In this post I intend to address how to use the format reporting options of the cucumberjs-browser tool to enable integration with the testling automated cross-browser testing tool to run your specs in various browser environment targets that you may not have installed on your own system.


For the purposes of this article, it is assumed that you are knowledgable of node and npm and familiar with creating feature specs for CucumberJS.

To view examples of features and step definitions for a browser-based application, please visit the cucumberjs-examples repo, from which this post will use to demonstrate integrating the generated testrunner from cucumberjs-browser with testling.


The cucumberjs-browser CLI tool provides the ability to run your feature specs in the browser by bundling your features, steps and support files - written in the usual way you would - to be run and evaluated at runtime by the browser-based CucumberJS testrunner

To install cucumberjs-browser:

$ npm install -g cucumberjs-browser

you may need to sudo

After installation, the cucumberjs-browser will be accessible on the command-line using cucumberjs-browser and can be run within any directory that has Features and Step Definitions (along with optional support files) that can be consumed by CucumberJS.

The cucumberjs-browser CLI tool can be run with the following options:

$ cucumberjs-browser [-o outdir] [-f format] [--tmpl template] [--features features]

Though it is strongly encouraged to provide a custom template using the --tmpl option, for the purpose of this article, we will focus on the format (-f) option. As of the writing of this article, the following format options are available:

  • ui
  • tap
  • testem
  • saucelabs

For the purpose of this article, we will be discussing the TAP format option value.

For more infromation about other format options, please visit the latest documentation regarding formats on the cucumberjs-browser.


The Test Anything Protocol is a specification for reporting test information. The benefit of using such a specification is that it can be consumed by any test harness that recognizes it.

You can output TAP reports from cucumberjs-browser using the tap value for the foromat option:

$ cucumberjs-browser -f tap

Running this command will generate the necessary files to print TAP test results in the console when loaded by a browser.

If you were to open the generated testrunner file in a browser using the example from cucumberjs-examples, you would see something like the following if you were to open the browser console:

TAP version 13
# Submit of valid item adds item to list
ok 1 I have opened the grocery list application
ok 2 I have an empty grocery list view
ok 3 I provide a valid grocery list item name
ok 4 I select to add an item
ok 5 The item is added to the grocery list view
# Submit of valid item adds item to collection
ok 6 I have opened the grocery list application
ok 7 I have an empty grocery list view
ok 8 I provide a valid grocery list item name
ok 9 I select to add an item
ok 10 The item is accessible from the grocery list collection
# Item added to grocery list
ok 11 I have opened the grocery list application
ok 12 I have an empty grocery list
ok 13 I add an item to the list
ok 14 The grocery list contains a single item
# Item accessible from grocery list
ok 15 I have opened the grocery list application
ok 16 I have an empty grocery list
ok 17 I add an item to the list
ok 18 I can access that item from the grocery list

# tests 18
# pass  18

# ok

It should be noted that the tap listener for cucumberjs-browser uses the excellent tape module.


I can't say enough how much I appreciate testling. You can install testling locally to run tests on the browsers installed on your system or use their remote service to run tests against various browsers that may not be available to you, yet are required as targets for your current project.


You can install testling to be run locally:

$ npm install -g testling

To run it, change directories into the generated files from cucumberjs-browser and run the following command:

$ cd browser-test
$ testling

That will consume a local package.json file and read a testling entry with options associated with running the generated html file againsta installed browsers on your system:



  "testling" : {
    "html" : "cucumber-testrunner.html",
    "browsers" : [


Truthfully, I never run testling locally. The main reasons being

a) I can automate the running of specs on locally installed browsers easier with other tools (this is for another post :) )
b) Testling provides a bigger benefit in providing tests against browsers I would otherwise have to install VMs for.

That said, I don't want ot pursuade you from using testling locally if it provides benefit in your workflow.


To use the remote service that testling provides, you still define the testling property in your package.json for the project as described above, but you additionally have to provide a webhook for your git repo in order to invoke the test harness. Upon a PUSH to your repository, testling will run the specified HTML file under the listed target browsers and report results based on the Test Anything Protocol output printed to console.

In addition to providing a great service, you also get the option of adding a nice looking badge to your project.

testling harness output

This badge was produced by pushing an update to the cucumberjs-examples exampe repo with a defined webhook. (If you followed along in the previous articles, you will note that the failing IE tests are due to the use of Object.create in source without a polyfill).

_The process of adding a webhook to your project is described in better detail in the testling documentation._

If you do use testling in any fashion, I implore you to donate to the cause :)


In this article I introduced how the cucumberjs-browser CLI tool can be used to generate a browser-based testrunner to report tests in TAP format and integrate the invaluable testling service to run the tests on various browsers that may not be at your disposal otherwise.

While testling provides one consumer endpoint, using the TAP specification in reporting test results can easily be consumed by another test harness of your choice.

For more information on running CucumberJS in the browser and/or to report any issues, please visit the cucumberjs-browser repository.