UI Testing with nightwatch.js

Update 26 December 2016: The code in the repo https://github.com/matthewroach/nightwatch-demo, has been updated to run from a clone/download. All dependencies are part of the repository or part of the npm install.

Nightwatch.js is an easy to use Node.js based End-to-End (E2E) testing solution for browser based apps and websites. It uses the powerful Selenium WebDriver API to perform commands and assertions on DOM elements.

Testing your website as a user may interact with it may not be your first thought when talking about testing code. We can unit test our code to ensure it’s doing as it’s supposed to but the more code we apply to our UI the more dependency it will have from the UI and the code powering it.

Most of the code and web apps I create are driven from a server side language with a front end interface, and then JavaScript applied on top to add a nice user experience.

With UI testing or integration testing we can test all the parts of the web application are working as intended. Ever upgraded a third party library or decided to adjust a little bit of code on a single page to later get a bug report from someone that another page in the app is now not working? YES, unit testing should of caught these issues, one of the added benefits from using a UI testing tool is you can be 100% sure that the integration from the code and tests you have written work at the final stage of delivery.

Installing nightwatch.js

If you have node and npm installed on your machine, it’s pretty simply to get nightwatch set up, you can install it local to your application or as a global module (-g). I have installed mine globally. Just run the following from your command line (you may need to do this as an admin or sudo on a Mac):

npm install nightwatch -g

Once you have it installed you can confirm you have it install by checking the version

nightwatch -v
nightwatch v0.6.8

Setting up

The code and test’s are available on Github if you wish to look: https://github.com/matthewroach/nightwatch-demo

When using nightwatch.js you will need a nightwatch.json file, this is the config file that contains a lot of different options, for this post I’ll not cover them all, just the one’s I’ve used, changed or added. I have this file located at the route of my project, you can place it anywhere under your project but you’ll need to update config items to point to the relevant locations of your project.

I am using browserstack’s automate service to run my tests with. You don’t have to use browser stack to run these test’s you can use selenium to run them locally. Using selenium takes a bit more set up to get running, so for the purpose of this post we will use browser stack.

Below is the nightwatch.json file I have located at the root of my project. The src_folders config points to my tests folder that’s also located on the root of the project. You can change this to point to anywhere you like.

You will also notice some references to hub.browserstack.com, this tell’s nightwatch to use browser stack as our selenium running. The two items you need to update to use this is the browserstack.user and browserstack.key. You will find these in your browser stack account.

  "src_folders": ["tests"],
  "output_folder": "reports",
  "custom_commands_path": "",
  "custom_assertions_path": "",
  "page_objects_path": "",
  "globals_path": "",

"selenium": { "start_process": false, "server_path": "", "log_path": "", "host": "hub.browserstack.com", "port": 80, "cli_args": { "webdriver.chrome.driver": "", "webdriver.ie.driver": "" } },

"test_settings": { "default": { "launch_url": "http://hub.browserstack.com", "selenium_port" : 80, "selenium_host" : "hub.browserstack.com", "silent": true, "screenshots": { "enabled": false, "path": "" }, "desiredCapabilities": { "browserName": "chrome", "javascriptEnabled": true, "acceptSslCerts": true, "browserstack.user": "", "browserstack.key": "" } } } }


Test’s are written in JavaScript, I separate out my tests into a tests folder to keep separation from the app code. On bigger projects I’ve added extra folders with the tests folder to mimic the web app structure, so you are able to run selected areas on their own.

Each test file can have one or multiple test’s. Each test is a JavaScript function. A sample test is shown below:

module.exports = {
  'Login Page Initial Render': function( _browser ) {
    .waitForElementVisible( 'body', 1000 )
    .verify.value( 'input[type=submit]', 'Log In' )

The test shown above is very simple example that will open the URL: http://dev.matthewroach.me/login/ and check that the username and password fields are visible, the submit button has a value of Log In, and the error element is not visible.

One thing to note here is I am using the .verify object rather than the .assert object. The reason I prefer to use verify over assert is that the test’s will abort if you use assert, where as using verify it will record a fail on the test but carry on running through the other tests.

Running Tests

Now you have your first test and nightwatch all set up you can just call nightwatch from terminal in your project root, and you will see output like the following, you will noticed that it still outputs the test details even tho you are running test’s on browser stack. The output is also saved within browser stack, it looks slightly different in browser stack.

Nightwatch Output

When a test causes an error the output looks as follows

Nightwatch error output


Now you have the basics down, look at using page objects to make your tests DRY and reusable, see my post on UI Testing with nightwatch.js – Page Objects.