Here’s how I set up Karma & Jasmine to test a Batman.js app on Ruby on Rails.

(Actually, this is how we use it at work. Credit to Dan, as this is modeled after his work and blog post)

Warning: This is a bit hack-ish because it depends on your development server running while you run your tests. :)

Set Up Karma

You’ll need node and npm for this to work! Create the directory /spec/karma and put these files in it:

• package.json, which will tell npm what to install for you:

```json spec/karma/package.json { “name”: “your-app-name”, “version”: “0.0.1”, “engines”: { “node”: “>= 0.10” }, “dependencies”: { “karma”: “>= 0.10”, “karma-chrome-launcher”: “~0.1”, “karma-coffee-preprocessor”: “~0.1”, “karma-jasmine”: “~0.2” }, “devDependencies”: { “coffee-script”: “^1.7.1” } }

- `unit.coffee`, the configs for Karma:

```coffeescript spec/karma/unit.coffee
module.exports = (config) ->
  config.set
    basePath: '../../'
    frameworks: ['jasmine'] # that's my weapon of choice, anyways.
    plugins: [
      'karma-coffee-preprocessor'
      'karma-chrome-launcher'
      'karma-jasmine'
    ]
    preprocessors: {
      'spec/batman/**/*.coffee': ['coffee']
    }
    files: [
      'http://your-app.dev/assets/your-app.js' # point it at the app file on your dev server
      # yours might look like 'http://localhost:3000/assets/application.js' or something like that.
      # Of course, you can list as many files as you want here.
      'spec/batman/**/*.coffee' # load your tests
    ]
    reporters: ['dots']
    port: 9876
    colors: true
    logLevel: config.LOG_INFO
    autoWatch: true
    browsers: ['Chrome']
    captureTimeout: 60000
    singleRun: false

• run, a bash script to start the runner easily:

```bash spec/karma/run #!/bin/bash BASE_DIR=dirname $0 $BASE_DIR/node_modules/karma/bin/karma start $BASE_DIR/unit.coffee

from app root, just run $ ./karma/run to start the tests!

- Make `run` executable with `$ chmod +x spec/karma/run`.
- Add `spec/karma/node_modules` to `.gitignore` so you're not pushing around tons of Node modules with your project.
- Install Karma locally with `npm install spec/karma`.

You should be able to start the runner now with `$ spec/karma/run`. It will open a Chrome window if it's working.

# Write a Spec

I put my Batman.js specs in `spec/batman` with names corresponding to their location in `app/assets/batman`. You can do it however you want, but make sure you're loading the right files with `files` in `unit.coffee` above. Open up your first spec file, maybe `spec/batman/test_spec.coffee`, and put a jasmine spec in it:

```coffeescript spec/batman/test_spec.coffee
describe 'My test runner', ->
  it 'loaded Batman.js', ->
    expect(Batman).toBeDefined()
  it 'loaded my App', ->
    expect(App).toBeDefined() # <-- your app name!
  it 'loaded my Model', ->
    expect(App.Model).toBeDefined() # <-- your model name!

If those pass, you’re in business!

Using Batman.TestCase

Since Batman.TestCase is a Batman extra, you’ll need to include it in your project yourself. An easy way to do that is to include the src/extras/ directory from Github in your Rails app. For example, in /app/assets/batman/extras. Now, in your development server, visit /assets/extras/batman.test_case.js. Do you see the code for Batman.TestCase?

Now, just add that path to files in spec/karma/unit.coffee:

```coffeescript spec/karma/unit.coffee

…

files: [ “http://my-app.dev/assets/my_app.js” “http://my-app.dev/assets/extras/batman.test_case.js” “spec/batman/*/.coffee” ] #…

And if you want, make sure it's loaded with a jasmine spec:

```coffeescript spec/batman/test_case_spec.coffee
describe "Batman.TestCase is loaded", ->
  it "is defined", ->
    expect(Batman.TestCase).toBeDefined()

Not working?

• Did you make run executable by with $ chmod +x spec/karma/run?
• This is kind of a hacky setup – it depends on your development server (either $ rails server or Pow) running. Is it?
• In unit.coffee, files should list your tests, but it should also list compiled JS assets from your development server, including http:// and so on. Check the paths there in your browser. Do they contain everything you expect them to contain? You might need to add files to that list or add sprockets directives to those files so that they require other files.

Ok, well it ain’t perfect but it works. Hope it helps!