karma.conf.js

// Karma configuration
// Generated on Wed Nov 12 2014 16:58:10 GMT-0700 (MST)

module.exports = function(config) {
  config.set({

    // base path that will be used to resolve all patterns (eg. files, exclude)
    basePath: 'app',


    // frameworks to use
    // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
    frameworks: ['jasmine'],


    // list of files / patterns to load in the browser
    files: [
      'test/support/polymer_setup.js',
      {pattern: 'bower_components/**', included: false, served: true},
      {pattern: 'elements/**', included: false, served: true},
      'test/**/*-spec.js',
      'test/fixtures/*.html'
    ],


    // list of files to exclude
    exclude: [
    ],


    // preprocess matching files before serving them to the browser
    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
    preprocessors: {
      'test/fixtures/*.html': 'html2js'
    },


    // test results reporter to use
    // possible values: 'dots', 'progress'
    // available reporters: https://npmjs.org/browse/keyword/karma-reporter
    reporters: ['progress'],


    // web server port
    port: 9876,


    // enable / disable colors in the output (reporters and logs)
    colors: true,


    // level of logging
    // possible values: config.LOG_DISABLE || config.LOG_ERROR || config.LOG_WARN || config.LOG_INFO || config.LOG_DEBUG
    logLevel: config.LOG_INFO,


    // enable / disable watching file and executing tests whenever any file changes
    autoWatch: true,


    // start these browsers
    // available browser launchers: https://npmjs.org/browse/keyword/karma-launcher
    browsers: ['Chrome'],


    // Continuous Integration mode
    // if true, Karma captures browsers, runs the tests and exits
    singleRun: false
  });
};

output

Carls-MacBook-Pro:beehive carl$ ./node_modules/karma/bin/karma start karma.conf.js --single-run
INFO [karma]: Karma v0.12.24 server started at http://localhost:9876/
INFO [launcher]: Starting browser Chrome
INFO [Chrome 38.0.2125 (Mac OS X 10.10.0)]: Connected on socket W94OFEuw4CdgHVJQo-K6 with id 88824570
Chrome 38.0.2125 (Mac OS X 10.10.0) ERROR
  Uncaught TypeError: Cannot read property 'parentNode' of undefined
  at /Users/carl/Source/work/twt/beehive/app/bower_components/polymer/polymer.html:19

Chrome 38.0.2125 (Mac OS X 10.10.0) ERROR
  Uncaught ReferenceError: Platform is not defined
  at /Users/carl/Source/work/twt/beehive/app/bower_components/polymer/src/system/unresolved.js:30

polymer_setup.js

// 1. Load Polymer before any code that touches the DOM.
var script = document.createElement("script");
script.src = "/base/bower_components/webcomponentsjs/webcomponents.js";
document.getElementsByTagName("head")[0].appendChild(script);

// 2. Load component(s)
var link = document.createElement("link");
link.rel = "import";
link.href = "/base/elements/twt-user-badge.html";
document.getElementsByTagName("head")[0].appendChild(link);

// Delay Jasmine specs until WebComponentsReady
var POLYMER_READY = false;
beforeEach(function(done) {
  window.addEventListener('polymer-ready', function () {
    POLYMER_READY = true;
    done();
  });
  if (POLYMER_READY) done();
});

twt-user-badge-spec.js

describe('<twt-user-badge>', function () {
  describe('defaults', function () {
    var container;

    beforeEach(function () {
      container = document.createElement("div");
      container.innerHTML = __html__['test/fixtures/twt-user-badge.html'];
      document.body.appendChild(container);
      waits(0); // One event loop for elements to register in Polymer
    });

    afterEach(function () {
      document.body.removeChild(container);
    });

    describe('<twt-user-badge>', function () {
      it("should include the user's name", function () {
        var el = document.querySelector('twt-user-badge');
        expect(el.shadowRoot.textContent).toContain('George Stephanopoulos');
      });
    });
  });
});

twt-user-badge.html

<script>
  var user = {
    name: 'George Stephanopoulos',
    city: 'Copenhagen',
    country: 'DK'
  };
</script>
<twt-user-badge id="badge" user="{{user}}"></twt-user-badge>