Iamvery

The musings of a nerd


Unit Testing JavaScript

— Jan 27, 2015

Update - The jasmine-npm module and its README is an even more to the point example of this setup. Check it out https://github.com/jasmine/jasmine-npm.


TL;DR - I had to learn myself to unit test JavaScript recently. I made a repository to illustrate my findings.


I tend to lean heavily on TDD to realize the design of objects. I recently had to jump into some JavaScript and wanted the same advantage while writing it. I found it tricky to come about a unit testing setup, so this is the result of my afternoon experimenting. I’m fairly pleased with the result, but I wouldn’t trust it as idiomatic.

The Things

Node.js

The goto whenever you want to run JavaScript outside of the browser. I’m running this test suite from the command line.

Jasmine

The test framework I settled on is Jasmine. Currently, I really like the RSpec style of writing tests, and this scratches that itch in JavaScript world.

Grunt

I’m a command line guy, so I really want to be able to run these tests “headless”. Grunt is a JavaScript task runner that has a jasmine plugin for headless test runs.

To use Grunt on the command line, I also need to install the grunt-cli library.

Setup

Node.js

If you use Homebrew, the Node.js install is straight forward:

$ brew install node

Node Modules

Once node is installed, I use npm (“node package manager”) to install the JavaScript dependencies. These are stored in a file named package.json in the root directory of your project. Here are the dependencies for our simple test suite:

Install the JavaScript dependencies:

$ npm install

Create Gruntfile.js

This file configures the Grunt task runner. Here is a simple configuration:

This file looks for JavaScript files in the ./lib directory and finds spec files named *Spec.js in the ./spec/lib directory.

Run the suite

I skipped over adding specs in this post. Checkout my example repo for a simple, complete example. You can run the test suite with this command:

$ grunt jasmine

You should see output like:

Running "jasmine:tappy" (jasmine) task
Testing jasmine specs via PhantomJS

 Thing
   ✓ does stuff

1 spec in 0.004s.
>> 0 failures

Done, without errors.

That’s all, folks

Let me know if you have any questions in the comments! I may not know the answer, but I love opportunities to learn!

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