Setup karma to test a node.js module?

Question

I'm developing a Node.js module, and I want to use Karma to auto-test it while working.

In my config file, I setup this:

// list of files / patterns to load in the browser
files: [
  './index.js',
  './test/indexSpecs.js'
],

Obviously, since Node.js isn't included in the browser files, I get this error:

Uncaught ReferenceError: require is not defined

If i add:

files: [
  './node_modules/**/*.js',
  './index.js',
  './test/indexSpecs.js'
],

I get a bunch of errors. I think js files get loaded in alphabetical order, which is wrong.

I also think that Node.js cannot be run in a browser, so what I'm trying to do may be totally wrong. Is there an alternative?

Answer 1

I'm developing a Node.js module, and I want to use Karma to auto-test it while working.

You should not. Karma is designed for client-side code.

To auto-test your code, the simplest way is to create a npm script similar to this one (with mocha):

"scripts": {
    "test": "mocha ./**",
    "test:watch": "npm run test -- -w"
}

Then, use npm test to run the tests on demand, or npm run test:watch to continuously run the tests.

You can also use a grunt or gulp script with a watch task if you prefer.

Answer 2

You are right about karma not being a good fit for testing server side code. It is going to run everything in the context of a browser, which is causing the issues you are seeing. If you wanted to develop a module for the server and the client you could use karma in conjunction with browserfiy, but you would still need to run the tests in a node environment.

Instead, I would suggest using mocha : a simple and powerful test runner that works great for testing node modules.