Neutrino Karma Preset

@neutrinojs/karma is a Neutrino preset that supports testing web applications using the Karma test runner.

Features

• Zero upfront configuration necessary to start testing on real browsers with Karma, Mocha, and Chrome Headless
• Babel compilation that compiles your tests using the same Babel options used by your source code
• Source watching for re-running of tests on change
• Out-of-the-box support for running in CI
• Easily extensible to customize your testing as needed

Requirements

• Node.js v6.10+
• Yarn or npm client
• Neutrino v8, Neutrino build preset

Installation

@neutrinojs/karma can be installed via the Yarn or npm clients. Inside your project, make sure neutrino and @neutrinojs/karma are development dependencies. You will also be using another Neutrino preset for building your application source code.

Yarn

❯ yarn add --dev @neutrinojs/karma

npm

❯ npm install --save-dev @neutrinojs/karma

Project Layout

@neutrinojs/karma follows the standard project layout specified by Neutrino. This means that by default all project test code should live in a directory named test in the root of the project. Test files end in _test.js by default.

Quickstart

After adding the Karma preset to your Neutrino-built project, add a new directory named test in the root of the project, with a single JS file named simple_test.js in it.

❯ mkdir test && touch test/simple_test.js

Edit your test/simple_test.js file with the following:

import assert from 'assert';

describe('simple', () => {
  it('should be sane', () => {
    assert.equal(true, !false);
  });
});

Now edit your project's package.json to add commands for testing your application. In this example, let's pretend this is a React project:

{
  "scripts": {
    "test": "neutrino test --use @neutrinojs/react @neutrinojs/karma"
  }
}

Or if you are using .neutrinorc.js, add this preset to your use array instead of --use flags:

module.exports = {
  use: [
    '@neutrinojs/react',
    '@neutrinojs/karma'
  ]
}

Run the tests, and view the results in your console:

Yarn

❯ yarn test

START:
21 11 2017 06:56:39.804:INFO [karma]: Karma v1.7.1 server started at http://0.0.0.0:9876/
21 11 2017 06:56:39.806:INFO [launcher]: Launching browser ChromeHeadless with unlimited concurrency
21 11 2017 06:56:39.809:INFO [launcher]: Starting browser ChromeHeadless
21 11 2017 06:56:40.170:INFO [HeadlessChrome 0.0.0 (Mac OS X 10.13.0)]: Connected on socket PW-kCVej8pQuT-HAAAAA with id 14691980
  simple
    ✔ should be sane

Finished in 0.005 secs / 0 secs @ 06:56:40 GMT-0600 (CST)

SUMMARY:
✔ 1 test completed

npm

❯ npm test

START:
21 11 2017 06:56:39.804:INFO [karma]: Karma v1.7.1 server started at http://0.0.0.0:9876/
21 11 2017 06:56:39.806:INFO [launcher]: Launching browser ChromeHeadless with unlimited concurrency
21 11 2017 06:56:39.809:INFO [launcher]: Starting browser ChromeHeadless
21 11 2017 06:56:40.170:INFO [HeadlessChrome 0.0.0 (Mac OS X 10.13.0)]: Connected on socket PW-kCVej8pQuT-HAAAAA with id 14691980
  simple
    ✔ should be sane

Finished in 0.005 secs / 0 secs @ 06:56:40 GMT-0600 (CST)

SUMMARY:
✔ 1 test completed

To run tests against files from your source code, simply import them:

import thingToTest from '../src/thing';

For more details on specific Karma usage, please refer to their documentation.

Executing single tests

By default this preset will execute every test file located in your test directory ending in the appropriate file extension. Use the command line files parameters to execute individual tests.

Watching for changes

@neutrinojs/karma can watch for changes on your source directory and subsequently re-run tests. Simply use the --watch flag with your neutrino test command.

Preset options

You can provide custom options and have them merged with this preset's default options, which are subsequently passed to Karma. You can modify Karma settings from .neutrinorc.js by overriding with any options Karma accepts. In a standalone Karma project this is typically done in a karma.conf.js or similar file, but @neutrinojs/karma allows configuration through .neutrinorc.js as well. This accepts the same configuration options as outlined in the Karma documentation. Use an array pair instead of a string to supply these options.

Example: Change the duration Karma waits for a browser to reconnect (in ms).

module.exports = {
  use: [
    ['@neutrinojs/karma', { browserDisconnectTimeout: 5000 }]
  ]
};

If you wish to completely override the Karma configuration instead of it being merged, set the override property to true in the preset options:

module.exports = {
  use: [
    ['@neutrinojs/karma', {
      override: true,
      /* specify all other Karma configuration options */
    }]
  ]
};

Using from CI

@neutrinojs/karma needs no additional configuration to run your tests in CI infrastructure when using Chrome Headless. If you decide to use a browser with a display, you will need to ensure your CI can actually run the tests similar to a headless mode. This usually means having a display emulator and access to the browsers you are testing against.

For an example using Travis-CI and normal Chrome, you will need to add the following to your .travis.yml file:

before_install:
- export CHROME_BIN=chromium-browser
- export DISPLAY=:99.0
- sh -e /etc/init.d/xvfb start

You may also need to pass additional options to the Karma preset to change its behavior in CI, using standard Chrome as an example instead of Chrome Headless:

module.exports = {
  use: [
    ['@neutrinojs/karma', {
      browsers: [process.env.CI ? 'ChromeCI' : 'Chrome'],
      customLaunchers: {
        ChromeCI: {
          base: 'Chrome',
          flags: ['--no-sandbox']
        }
      },
    }]
  ]
}

Contributing

This preset is part of the neutrino-dev repository, a monorepo containing all resources for developing Neutrino and its core presets and middleware. Follow the contributing guide for details.