browser.js

(function () { 'use strict';

  var util_js = {
    get whenFrameworksReady () { return whenFrameworksReady; },
    get pluralizedStat () { return pluralizedStat; },
    get loadScript () { return loadScript; },
    get loadStyle () { return loadStyle; },
    get debug () { return debug; },
    get parseUrl () { return parseUrl; },
    get expandUrl () { return expandUrl; },
    get getParams () { return getParams; },
    get mergeParams () { return mergeParams; },
    get getParam () { return getParam; },
    get paramsToQuery () { return paramsToQuery; },
    get basePath () { return basePath; },
    get relativeLocation () { return relativeLocation; },
    get cleanLocation () { return cleanLocation; },
    get parallel () { return parallel; },
    get scriptPrefix () { return scriptPrefix; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */

  function whenFrameworksReady(callback) {
    debug('whenFrameworksReady');
    var done = function() {
      debug('whenFrameworksReady done');
      callback();
    };

    function importsReady() {
      window.removeEventListener('WebComponentsReady', importsReady);
      debug('WebComponentsReady');

      if (window.Polymer && Polymer.whenReady) {
        Polymer.whenReady(function() {
          debug('polymer-ready');
          done();
        });
      } else {
        done();
      }
    }

    // All our supported framework configurations depend on imports.
    if (!window.HTMLImports) {
      done();
    } else if (HTMLImports.ready) {
      importsReady();
    } else {
      window.addEventListener('WebComponentsReady', importsReady);
    }
  }

  /**
   * @param {number} count
   * @param {string} kind
   * @return {string} '<count> <kind> tests' or '<count> <kind> test'.
   */
  function pluralizedStat(count, kind) {
    if (count === 1) {
      return count + ' ' + kind + ' test';
    } else {
      return count + ' ' + kind + ' tests';
    }
  }

  /**
   * @param {string} path The URI of the script to load.
   * @param {function} done
   */
  function loadScript(path, done) {
    var script = document.createElement('script');
    script.src = path;
    if (done) {
      script.onload = done.bind(null, null);
      script.onerror = done.bind(null, 'Failed to load script ' + script.src);
    }
    document.head.appendChild(script);
  }

  /**
   * @param {string} path The URI of the stylesheet to load.
   * @param {function} done
   */
  function loadStyle(path, done) {
    var link = document.createElement('link');
    link.rel  = 'stylesheet';
    link.href = path;
    if (done) {
      link.onload = done.bind(null, null);
      link.onerror = done.bind(null, 'Failed to load stylesheet ' + link.href);
    }
    document.head.appendChild(link);
  }

  /**
   * @param {...*} var_args Logs values to the console when the `debug`
   *     configuration option is true.
   */
  function debug(var_args) {
    if (!config_js.get('verbose')) return;
    var args = [window.location.pathname];
    args.push.apply(args, arguments);
    (console.debug || console.log).apply(console, args);
  }

  // URL Processing

  /**
   * @param {string} url
   * @return {{base: string, params: string}}
   */
  function parseUrl(url) {
    var parts = url.match(/^(.*?)(?:\?(.*))?$/);
    return {
      base:   parts[1],
      params: this.getParams(parts[2] || ''),
    };
  }

  /**
   * Expands a URL that may or may not be relative to `base`.
   *
   * @param {string} url
   * @param {string} base
   * @return {string}
   */
  function expandUrl(url, base) {
    if (!base) return url;
    if (url.match(/^(\/|https?:\/\/)/)) return url;
    if (base.substr(base.length - 1) !== '/') {
      base = base + '/';
    }
    return base + url;
  }

  /**
   * @param {string=} opt_query A query string to parse.
   * @return {!Object<string, !Array<string>>} All params on the URL's query.
   */
  function getParams(opt_query) {
    var query = typeof opt_query === 'string' ? opt_query : window.location.search;
    if (query.substring(0, 1) === '?') {
      query = query.substring(1);
    }
    // python's SimpleHTTPServer tacks a `/` on the end of query strings :(
    if (query.slice(-1) === '/') {
      query = query.substring(0, query.length - 1);
    }
    if (query === '') return {};

    var result = {};
    query.split('&').forEach(function(part) {
      var pair = part.split('=');
      if (pair.length !== 2) {
        console.warn('Invalid URL query part:', part);
        return;
      }
      var key   = decodeURIComponent(pair[0]);
      var value = decodeURIComponent(pair[1]);

      if (!result[key]) {
        result[key] = [];
      }
      result[key].push(value);
    });

    return result;
  }

  /**
   * Merges params from `source` into `target` (mutating `target`).
   *
   * @param {!Object<string, !Array<string>>} target
   * @param {!Object<string, !Array<string>>} source
   */
  function mergeParams(target, source) {
    Object.keys(source).forEach(function(key) {
      if (!(key in target)) {
        target[key] = [];
      }
      target[key] = target[key].concat(source[key]);
    });
  }

  /**
   * @param {string} param The param to return a value for.
   * @return {?string} The first value for `param`, if found.
   */
  function getParam(param) {
    var params = getParams();
    return params[param] ? params[param][0] : null;
  }

  /**
   * @param {!Object<string, !Array<string>>} params
   * @return {string} `params` encoded as a URI query.
   */
  function paramsToQuery(params) {
    var pairs = [];
    Object.keys(params).forEach(function(key) {
      params[key].forEach(function(value) {
        pairs.push(encodeURIComponent(key) + '=' + encodeURIComponent(value));
      });
    });
    return '?' + pairs.join('&');
  }

  /**
   * @param {!Location|string} location
   * @return {string}
   */
  function basePath(location) {
    return (location.pathname || location).match(/^.*\//)[0];
  }

  /**
   * @param {!Location|string} location
   * @param {string} basePath
   * @return {string}
   */
  function relativeLocation(location, basePath) {
    var path = location.pathname || location;
    if (path.indexOf(basePath) === 0) {
      path = path.substring(basePath.length);
    }
    return path;
  }

  /**
   * @param {!Location|string} location
   * @return {string}
   */
  function cleanLocation(location) {
    var path = location.pathname || location;
    if (path.slice(-11) === '/index.html') {
      path = path.slice(0, path.length - 10);
    }
    return path;
  }

  /**
   * Like `async.parallelLimit`, but our own so that we don't force a dependency
   * on downstream code.
   *
   * @param {!Array<function(function(*))>} runners Runners that call their given
   *     Node-style callback when done.
   * @param {number|function(*)} limit Maximum number of concurrent runners.
   *     (optional).
   * @param {?function(*)} done Callback that should be triggered once all runners
   *     have completed, or encountered an error.
   */
  function parallel(runners, limit, done) {
    if (typeof limit !== 'number') {
      done  = limit;
      limit = 0;
    }
    if (!runners.length) return done();

    var called    = false;
    var total     = runners.length;
    var numActive = 0;
    var numDone   = 0;

    function runnerDone(error) {
      if (called) return;
      numDone = numDone + 1;
      numActive = numActive - 1;

      if (error || numDone >= total) {
        called = true;
        done(error);
      } else {
        runOne();
      }
    }

    function runOne() {
      if (limit && numActive >= limit) return;
      if (!runners.length) return;
      numActive = numActive + 1;
      runners.shift()(runnerDone);
    }
    runners.forEach(runOne);
  }

  /**
   * Finds the directory that a loaded script is hosted on.
   *
   * @param {string} filename
   * @return {string?}
   */
  function scriptPrefix(filename) {
    var scripts = document.querySelectorAll('script[src*="' + filename + '"]');
    if (scripts.length !== 1) return null;
    var script = scripts[0].src;
    return script.substring(0, script.indexOf(filename));
  }

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  function ChildRunner(url, parentScope) {
    var urlBits = util_js.parseUrl(url);
    util_js.mergeParams(
        urlBits.params, util_js.getParams(parentScope.location.search));
    delete urlBits.params.cli_browser_id;

    this.url         = urlBits.base + util_js.paramsToQuery(urlBits.params);
    this.parentScope = parentScope;

    this.state = 'initializing';
  }

  // ChildRunners get a pretty generous load timeout by default.
  ChildRunner.loadTimeout = 30000;

  // We can't maintain properties on iframe elements in Firefox/Safari/???, so we
  // track childRunners by URL.
  ChildRunner._byUrl = {};

  /**
   * @return {ChildRunner} The `ChildRunner` that was registered for this window.
   */
  ChildRunner.current = function() {
    return ChildRunner.get(window);
  };

  /**
   * @param {!Window} target A window to find the ChildRunner of.
   * @param {boolean} traversal Whether this is a traversal from a child window.
   * @return {ChildRunner} The `ChildRunner` that was registered for `target`.
   */
  ChildRunner.get = function(target, traversal) {
    var childRunner = ChildRunner._byUrl[target.location.href];
    if (childRunner) return childRunner;
    if (window.parent === window) {  // Top window.
      if (traversal) {
        console.warn('Subsuite loaded but was never registered. This most likely is due to wonky history behavior. Reloading...');
        window.location.reload();
      }
      return null;
    }
    // Otherwise, traverse.
    return window.parent.WCT._ChildRunner.get(target, true);
  };

  /**
   * Loads and runs the subsuite.
   *
   * @param {function} done Node-style callback.
   */
  ChildRunner.prototype.run = function(done) {
    util_js.debug('ChildRunner#run', this.url);
    this.state = 'loading';
    this.onRunComplete = done;

    this.iframe = document.createElement('iframe');
    this.iframe.src = this.url;
    this.iframe.classList.add('subsuite');

    var container = document.getElementById('subsuites');
    if (!container) {
      container = document.createElement('div');
      container.id = 'subsuites';
      document.body.appendChild(container);
    }
    container.appendChild(this.iframe);

    // let the iframe expand the URL for us.
    this.url = this.iframe.src;
    ChildRunner._byUrl[this.url] = this;

    this.timeoutId = setTimeout(
        this.loaded.bind(this, new Error('Timed out loading ' + this.url)), ChildRunner.loadTimeout);

    this.iframe.addEventListener('error',
        this.loaded.bind(this, new Error('Failed to load document ' + this.url)));

    this.iframe.contentWindow.addEventListener('DOMContentLoaded', this.loaded.bind(this, null));
  };

  /**
   * Called when the sub suite's iframe has loaded (or errored during load).
   *
   * @param {*} error The error that occured, if any.
   */
  ChildRunner.prototype.loaded = function(error) {
    util_js.debug('ChildRunner#loaded', this.url, error);

    // Not all targets have WCT loaded (compatiblity mode)
    if (this.iframe.contentWindow.WCT) {
      this.share = this.iframe.contentWindow.WCT.share;
    }

    if (error) {
      this.signalRunComplete(error);
      this.done();
    }
  };

  /**
   * Called in mocha/run.js when all dependencies have loaded, and the child is
   * ready to start running tests
   *
   * @param {*} error The error that occured, if any.
   */
  ChildRunner.prototype.ready = function(error) {
    util_js.debug('ChildRunner#ready', this.url, error);
    if (this.timeoutId) {
      clearTimeout(this.timeoutId);
    }
    if (error) {
      this.signalRunComplete(error);
      this.done();
    }
  };

  /** Called when the sub suite's tests are complete, so that it can clean up. */
  ChildRunner.prototype.done = function done() {
    util_js.debug('ChildRunner#done', this.url, arguments);

    this.signalRunComplete();

    if (!this.iframe) return;
    // Be safe and avoid potential browser crashes when logic attempts to interact
    // with the removed iframe.
    setTimeout(function() {
      this.iframe.parentNode.removeChild(this.iframe);
      this.iframe = null;
    }.bind(this), 1);
  };

  ChildRunner.prototype.signalRunComplete = function signalRunComplete(error) {
    if (!this.onRunComplete) return;
    this.state = 'complete';
    this.onRunComplete(error);
    this.onRunComplete = null;
  };

  var config_js = {
    get _config () { return _config; },
    get setup () { return setup; },
    get get () { return get; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var _config = {
    /**
     * `.js` scripts to be loaded (synchronously) before WCT starts in earnest.
     *
     * Paths are relative to `scriptPrefix`.
     */
    environmentScripts: [
      // https://github.com/PolymerLabs/stacky/issues/2
      'stacky/lib/parsing.js',
      'stacky/lib/formatting.js',
      'stacky/lib/normalization.js',
      'async/lib/async.js',
      'lodash/lodash.js',
      'mocha/mocha.js',
      'chai/chai.js',
      'sinonjs/sinon.js',
      'sinon-chai/lib/sinon-chai.js',
      'accessibility-developer-tools/dist/js/axs_testing.js'
    ],

    /** Absolute root for client scripts. Detected in `setup()` if not set. */
    root: null,

    /** By default, we wait for any web component frameworks to load. */
    waitForFrameworks: true,

    /** How many `.html` suites that can be concurrently loaded & run. */
    numConcurrentSuites: 1,

    /** Whether `console.error` should be treated as a test failure. */
    trackConsoleError: true,

    /** Configuration passed to mocha.setup. */
    mochaOptions: {
      timeout: 10 * 1000
    },

    /** Whether WCT should emit (extremely verbose) debugging log messages. */
    verbose: false,
  };

  /**
   * Merges initial `options` into WCT's global configuration.
   *
   * @param {Object} options The options to merge. See `browser/config.js` for a
   *     reference.
   */
  function setup(options) {
    var childRunner = ChildRunner.current();
    if (childRunner) {
      _deepMerge(_config, childRunner.parentScope.WCT._config);
      // But do not force the mocha UI
      delete _config.mochaOptions.ui;
    }

    if (options && typeof options === 'object') {
      _deepMerge(_config, options);
    }

    if (!_config.root) {
      // Sibling dependencies.
      var root = util_js.scriptPrefix('browser.js');
      _config.root = util_js.basePath(root.substr(0, root.length - 1));
      if (!_config.root) {
        throw new Error('Unable to detect root URL for WCT sources. Please set WCT.root before including browser.js');
      }
    }
  }

  /**
   * Retrieves a configuration value.
   *
   * @param {string} key
   * @return {*}
   */
  function get(key) {
    return _config[key];
  }

  // Internal

  function _deepMerge(target, source) {
    Object.keys(source).forEach(function(key) {
      if (target[key] !== null && typeof target[key] === 'object' && !Array.isArray(target[key])) {
        _deepMerge(target[key], source[key]);
      } else {
        target[key] = source[key];
      }
    });
  }

  var suites_js = {
    get htmlSuites () { return suites_js__htmlSuites; },
    get jsSuites () { return suites_js__jsSuites; },
    get loadSuites () { return loadSuites; },
    get activeChildSuites () { return activeChildSuites; },
    get loadJsSuites () { return loadJsSuites; },
    get runSuites () { return runSuites; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var suites_js__htmlSuites = [];
  var suites_js__jsSuites   = [];

  // We process grep ourselves to avoid loading suites that will be filtered.
  var GREP = util_js.getParam('grep');

  /**
   * Loads suites of tests, supporting both `.js` and `.html` files.
   *
   * @param {!Array.<string>} files The files to load.
   */
  function loadSuites(files) {
    files.forEach(function(file) {
      if (/\.js(\?.*)?$/.test(file)) {
        suites_js__jsSuites.push(file);
      } else if (/\.html(\?.*)?$/.test(file)) {
        suites_js__htmlSuites.push(file);
      } else {
        throw new Error('Unknown resource type: ' + file);
      }
    });
  }

  /**
   * @return {!Array.<string>} The child suites that should be loaded, ignoring
   *     those that would not match `GREP`.
   */
  function activeChildSuites() {
    var subsuites = suites_js__htmlSuites;
    if (GREP) {
      var cleanSubsuites = [];
      for (var i = 0, subsuite; subsuite = subsuites[i]; i++) {
        if (GREP.indexOf(util_js.cleanLocation(subsuite)) !== -1) {
          cleanSubsuites.push(subsuite);
        }
      }
      subsuites = cleanSubsuites;
    }
    return subsuites;
  }

  /**
   * Loads all `.js` sources requested by the current suite.
   *
   * @param {!MultiReporter} reporter
   * @param {function} done
   */
  function loadJsSuites(reporter, done) {
    util_js.debug('loadJsSuites', suites_js__jsSuites);

    var loaders = suites_js__jsSuites.map(function(file) {
      // We only support `.js` dependencies for now.
      return util_js.loadScript.bind(util_js, file);
    });

    util_js.parallel(loaders, done);
  }

  /**
   * @param {!MultiReporter} reporter
   * @param {!Array.<string>} childSuites
   * @param {function} done
   */
  function runSuites(reporter, childSuites, done) {
    util_js.debug('runSuites');

    var suiteRunners = [
      // Run the local tests (if any) first, not stopping on error;
      _runMocha.bind(null, reporter),
    ];

    // As well as any sub suites. Again, don't stop on error.
    childSuites.forEach(function(file) {
      suiteRunners.push(function(next) {
        var childRunner = new ChildRunner(file, window);
        reporter.emit('childRunner start', childRunner);
        childRunner.run(function(error) {
          reporter.emit('childRunner end', childRunner);
          if (error) reporter.emitOutOfBandTest(file, error);
          next();
        });
      });
    });

    util_js.parallel(suiteRunners, config_js.get('numConcurrentSuites'), function(error) {
      reporter.done();
      done(error);
    });
  }

  /**
   * Kicks off a mocha run, waiting for frameworks to load if necessary.
   *
   * @param {!MultiReporter} reporter Where to send Mocha's events.
   * @param {function} done A callback fired, _no error is passed_.
   */
  function _runMocha(reporter, done, waited) {
    if (config_js.get('waitForFrameworks') && !waited) {
      util_js.whenFrameworksReady(_runMocha.bind(null, reporter, done, true));
      return;
    }
    util_js.debug('_runMocha');
    var mocha = window.mocha;
    var Mocha = window.Mocha;

    mocha.reporter(reporter.childReporter(window.location));
    mocha.suite.title = reporter.suiteTitle(window.location);
    mocha.grep(GREP);

    // We can't use `mocha.run` because it bashes over grep, invert, and friends.
    // See https://github.com/visionmedia/mocha/blob/master/support/tail.js#L137
    var runner = Mocha.prototype.run.call(mocha, function(error) {
      if (document.getElementById('mocha')) {
        Mocha.utils.highlightTags('code');
      }
      done();  // We ignore the Mocha failure count.
    });

    // Mocha's default `onerror` handling strips the stack (to support really old
    // browsers). We upgrade this to get better stacks for async errors.
    //
    // TODO(nevir): Can we expand support to other browsers?
    if (navigator.userAgent.match(/chrome/i)) {
      window.onerror = null;
      window.addEventListener('error', function(event) {
        if (!event.error) return;
        if (event.error.ignore) return;
        runner.uncaught(event.error);
      });
    }
  }

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var ConsoleReporter__console = window.console;

  var FONT = ';font: normal 13px "Roboto", "Helvetica Neue", "Helvetica", sans-serif;';
  var STYLES = {
    plain:   FONT,
    suite:   'color: #5c6bc0' + FONT,
    test:    FONT,
    passing: 'color: #259b24' + FONT,
    pending: 'color: #e65100' + FONT,
    failing: 'color: #c41411' + FONT,
    stack:   'color: #c41411',
    results: FONT + 'font-size: 16px',
  };

  // I don't think we can feature detect this one...
  var userAgent = navigator.userAgent.toLowerCase();
  var CAN_STYLE_LOG   = userAgent.match('firefox') || userAgent.match('webkit');
  var CAN_STYLE_GROUP = userAgent.match('webkit');
  // Track the indent for faked `console.group`
  var logIndent = '';

  function log(text, style) {
    text = text.split('\n').map(function(l) { return logIndent + l; }).join('\n');
    if (CAN_STYLE_LOG) {
      ConsoleReporter__console.log('%c' + text, STYLES[style] || STYLES.plain);
    } else {
      ConsoleReporter__console.log(text);
    }
  }

  function logGroup(text, style) {
    if (CAN_STYLE_GROUP) {
      ConsoleReporter__console.group('%c' + text, STYLES[style] || STYLES.plain);
    } else if (ConsoleReporter__console.group) {
      ConsoleReporter__console.group(text);
    } else {
      logIndent = logIndent + '  ';
      log(text, style);
    }
  }

  function logGroupEnd() {
    if (ConsoleReporter__console.groupEnd) {
      ConsoleReporter__console.groupEnd();
    } else {
      logIndent = logIndent.substr(0, logIndent.length - 2);
    }
  }

  function logException(error) {
    log(error.stack || error.message || error, 'stack');
  }

  /**
   * A Mocha reporter that logs results out to the web `console`.
   *
   * @param {!Mocha.Runner} runner The runner that is being reported on.
   */
  function Console(runner) {
    Mocha.reporters.Base.call(this, runner);

    runner.on('suite', function(suite) {
      if (suite.root) return;
      logGroup(suite.title, 'suite');
    }.bind(this));

    runner.on('suite end', function(suite) {
      if (suite.root) return;
      logGroupEnd();
    }.bind(this));

    runner.on('test', function(test) {
      logGroup(test.title, 'test');
    }.bind(this));

    runner.on('pending', function(test) {
      logGroup(test.title, 'pending');
    }.bind(this));

    runner.on('fail', function(test, error) {
      logException(error);
    }.bind(this));

    runner.on('test end', function(test) {
      logGroupEnd();
    }.bind(this));

    runner.on('end', this.logSummary.bind(this));
  }

  /** Prints out a final summary of test results. */
  Console.prototype.logSummary = function logSummary() {
    logGroup('Test Results', 'results');

    if (this.stats.failures > 0) {
      log(util_js.pluralizedStat(this.stats.failures, 'failing'), 'failing');
    }
    if (this.stats.pending > 0) {
      log(util_js.pluralizedStat(this.stats.pending, 'pending'), 'pending');
    }
    log(util_js.pluralizedStat(this.stats.passes, 'passing'));

    if (!this.stats.failures) {
      log('test suite passed', 'passing');
    }
    log('Evaluated ' + this.stats.tests + ' tests in ' + this.stats.duration + 'ms.');
    logGroupEnd();
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */

  /**
   * WCT-specific behavior on top of Mocha's default HTML reporter.
   *
   * @param {!Mocha.Runner} runner The runner that is being reported on.
   */
  function HTML(runner) {
    var output = document.createElement('div');
    output.id = 'mocha';
    document.body.appendChild(output);

    runner.on('suite', function(test) {
      this.total = runner.total;
    }.bind(this));

    Mocha.reporters.HTML.call(this, runner);
  }

  // Woo! What a hack. This just saves us from adding a bunch of complexity around
  // style loading.
  var style = document.createElement('style');
  style.textContent = 'html, body {' +
                      '  position: relative;' +
                      '  height: 100%;' +
                      '  width:  100%;' +
                      '  min-width: 900px;' +
                      '}' +
                      '#mocha, #subsuites {' +
                      '  height: 100%;' +
                      '  position: absolute;' +
                      '  top: 0;' +
                      '}' +
                      '#mocha {' +
                      '  box-sizing: border-box;' +
                      '  margin: 0 !important;' +
                      '  overflow-y: auto;' +
                      '  padding: 60px 20px;' +
                      '  right: 0;' +
                      '  left: 500px;' +
                      '}' +
                      '#subsuites {' +
                      '  -ms-flex-direction: column;' +
                      '  -webkit-flex-direction: column;' +
                      '  display: -ms-flexbox;' +
                      '  display: -webkit-flex;' +
                      '  display: flex;' +
                      '  flex-direction: column;' +
                      '  left: 0;' +
                      '  width: 500px;' +
                      '}' +
                      '#subsuites .subsuite {' +
                      '  border: 0;' +
                      '  width: 100%;' +
                      '  height: 100%;' +
                      '}' +
                      '#mocha .test.pass .duration {' +
                      '  color: #555 !important;' +
                      '}';
  document.head.appendChild(style);

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var STACKY_CONFIG = {
    indent: '  ',
    locationStrip: [
      /^https?:\/\/[^\/]+/,
      /\?.*$/,
    ],
    filter: function(line) {
      return line.location.match(/\/web-component-tester\/[^\/]+(\?.*)?$/);
    },
  };

  // https://github.com/visionmedia/mocha/blob/master/lib/runner.js#L36-46
  var MOCHA_EVENTS = [
    'start',
    'end',
    'suite',
    'suite end',
    'test',
    'test end',
    'hook',
    'hook end',
    'pass',
    'fail',
    'pending',
  ];

  // Until a suite has loaded, we assume this many tests in it.
  var ESTIMATED_TESTS_PER_SUITE = 3;

  /**
   * A Mocha-like reporter that combines the output of multiple Mocha suites.
   *
   * @param {number} numSuites The number of suites that will be run, in order to
   *     estimate the total number of tests that will be performed.
   * @param {!Array.<!Mocha.reporters.Base>} reporters The set of reporters that
   *     should receive the unified event stream.
   * @param {MultiReporter} parent The parent reporter, if present.
   */
  function MultiReporter(numSuites, reporters, parent) {
    this.reporters = reporters.map(function(reporter) {
      return new reporter(this);
    }.bind(this));

    this.parent = parent;
    this.basePath = parent && parent.basePath || util_js.basePath(window.location);

    this.total = numSuites * ESTIMATED_TESTS_PER_SUITE;
    // Mocha reporters assume a stream of events, so we have to be careful to only
    // report on one runner at a time...
    this.currentRunner = null;
    // ...while we buffer events for any other active runners.
    this.pendingEvents = [];

    this.emit('start');
  }

  /**
   * @param {!Location|string} location The location this reporter represents.
   * @return {!Mocha.reporters.Base} A reporter-like "class" for each child suite
   *     that should be passed to `mocha.run`.
   */
  MultiReporter.prototype.childReporter = function childReporter(location) {
    var name = this.suiteTitle(location);
    // The reporter is used as a constructor, so we can't depend on `this` being
    // properly bound.
    var self = this;
    function reporter(runner) {
      runner.name = name;
      self.bindChildRunner(runner);
    }
    reporter.title = name;
    return reporter;
  };

  /** Must be called once all runners have finished. */
  MultiReporter.prototype.done = function done() {
    this.complete = true;
    this.flushPendingEvents();
    this.emit('end');
  };

  /**
   * Emit a top level test that is not part of any suite managed by this reporter.
   *
   * Helpful for reporting on global errors, loading issues, etc.
   *
   * @param {string} title The title of the test.
   * @param {*} opt_error An error associated with this test. If falsy, test is
   *     considered to be passing.
   * @param {string} opt_suiteTitle Title for the suite that's wrapping the test.
   * @param {?boolean} opt_estimated If this test was included in the original
   *     estimate of `numSuites`.
   */
  MultiReporter.prototype.emitOutOfBandTest = function emitOutOfBandTest(title, opt_error, opt_suiteTitle, opt_estimated) {
    util_js.debug('MultiReporter#emitOutOfBandTest(', arguments, ')');
    var root = new Mocha.Suite();
    root.title = opt_suiteTitle || '';
    var test = new Mocha.Test(title, function() {
    });
    test.parent = root;
    test.state  = opt_error ? 'failed' : 'passed';
    test.err    = opt_error;

    if (!opt_estimated) {
      this.total = this.total + ESTIMATED_TESTS_PER_SUITE;
    }

    var runner = {total: 1};
    this.proxyEvent('start', runner);
    this.proxyEvent('suite', runner, root);
    this.proxyEvent('test', runner, test);
    if (opt_error) {
      this.proxyEvent('fail', runner, test, opt_error);
    } else {
      this.proxyEvent('pass', runner, test);
    }
    this.proxyEvent('test end', runner, test);
    this.proxyEvent('suite end', runner, root);
    this.proxyEvent('end', runner);
  };

  /**
   * @param {!Location|string} location
   * @return {string}
   */
  MultiReporter.prototype.suiteTitle = function suiteTitle(location) {
    var path = util_js.relativeLocation(location, this.basePath);
    path = util_js.cleanLocation(path);
    return path;
  };

  // Internal Interface

  /** @param {!Mocha.runners.Base} runner The runner to listen to events for. */
  MultiReporter.prototype.bindChildRunner = function bindChildRunner(runner) {
    MOCHA_EVENTS.forEach(function(eventName) {
      runner.on(eventName, this.proxyEvent.bind(this, eventName, runner));
    }.bind(this));
  };

  /**
   * Evaluates an event fired by `runner`, proxying it forward or buffering it.
   *
   * @param {string} eventName
   * @param {!Mocha.runners.Base} runner The runner that emitted this event.
   * @param {...*} var_args Any additional data passed as part of the event.
   */
  MultiReporter.prototype.proxyEvent = function proxyEvent(eventName, runner, var_args) {
    var extraArgs = Array.prototype.slice.call(arguments, 2);
    if (this.complete) {
      console.warn('out of order Mocha event for ' + runner.name + ':', eventName, extraArgs);
      return;
    }

    if (this.currentRunner && runner !== this.currentRunner) {
      this.pendingEvents.push(arguments);
      return;
    }
    util_js.debug('MultiReporter#proxyEvent(', arguments, ')');

    // This appears to be a Mocha bug: Tests failed by passing an error to their
    // done function don't set `err` properly.
    //
    // TODO(nevir): Track down.
    if (eventName === 'fail' && !extraArgs[0].err) {
      extraArgs[0].err = extraArgs[1];
    }

    if (eventName === 'start') {
      this.onRunnerStart(runner);
    } else if (eventName === 'end') {
      this.onRunnerEnd(runner);
    } else {
      this.cleanEvent(eventName, runner, extraArgs);
      this.emit.apply(this, [eventName].concat(extraArgs));
    }
  };

  /**
   * Cleans or modifies an event if needed.
   *
   * @param {string} eventName
   * @param {!Mocha.runners.Base} runner The runner that emitted this event.
   * @param {!Array.<*>} extraArgs
   */
  MultiReporter.prototype.cleanEvent = function cleanEvent(eventName, runner, extraArgs) {
    // Suite hierarchy
    if (extraArgs[0]) {
      extraArgs[0] = this.showRootSuite(extraArgs[0]);
    }

    // Normalize errors
    if (eventName === 'fail') {
      extraArgs[1] = Stacky.normalize(extraArgs[1], STACKY_CONFIG);
    }
    if (extraArgs[0] && extraArgs[0].err) {
      extraArgs[0].err = Stacky.normalize(extraArgs[0].err, STACKY_CONFIG);
    }
  };

  /**
   * We like to show the root suite's title, which requires a little bit of
   * trickery in the suite hierarchy.
   *
   * @param {!Mocha.Runnable} node
   */
  MultiReporter.prototype.showRootSuite = function showRootSuite(node) {
    var leaf = node = Object.create(node);
    while (node && node.parent) {
      var wrappedParent = Object.create(node.parent);
      node.parent = wrappedParent;
      node = wrappedParent;
    }
    node.root = false;

    return leaf;
  };

  /** @param {!Mocha.runners.Base} runner */
  MultiReporter.prototype.onRunnerStart = function onRunnerStart(runner) {
    util_js.debug('MultiReporter#onRunnerStart:', runner.name);
    this.total = this.total - ESTIMATED_TESTS_PER_SUITE + runner.total;
    this.currentRunner = runner;
  };

  /** @param {!Mocha.runners.Base} runner */
  MultiReporter.prototype.onRunnerEnd = function onRunnerEnd(runner) {
    util_js.debug('MultiReporter#onRunnerEnd:', runner.name);
    this.currentRunner = null;
    this.flushPendingEvents();
  };

  /**
   * Flushes any buffered events and runs them through `proxyEvent`. This will
   * loop until all buffered runners are complete, or we have run out of buffered
   * events.
   */
  MultiReporter.prototype.flushPendingEvents = function flushPendingEvents() {
    var events = this.pendingEvents;
    this.pendingEvents = [];
    events.forEach(function(eventArgs) {
      this.proxyEvent.apply(this, eventArgs);
    }.bind(this));
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var ARC_OFFSET = 0; // start at the right.
  var ARC_WIDTH  = 6;

  /**
   * A Mocha reporter that updates the document's title and favicon with
   * at-a-glance stats.
   *
   * @param {!Mocha.Runner} runner The runner that is being reported on.
   */
  function Title(runner) {
    Mocha.reporters.Base.call(this, runner);

    runner.on('test end', this.report.bind(this));
  }

  /** Reports current stats via the page title and favicon. */
  Title.prototype.report = function report() {
    this.updateTitle();
    this.updateFavicon();
  };

  /** Updates the document title with a summary of current stats. */
  Title.prototype.updateTitle = function updateTitle() {
    if (this.stats.failures > 0) {
      document.title = util_js.pluralizedStat(this.stats.failures, 'failing');
    } else {
      document.title = util_js.pluralizedStat(this.stats.passes, 'passing');
    }
  };

  /**
   * Draws an arc for the favicon status, relative to the total number of tests.
   *
   * @param {!CanvasRenderingContext2D} context
   * @param {number} total
   * @param {number} start
   * @param {number} length
   * @param {string} color
   */
  function drawFaviconArc(context, total, start, length, color) {
    var arcStart = ARC_OFFSET + Math.PI * 2 * (start / total);
    var arcEnd   = ARC_OFFSET + Math.PI * 2 * ((start + length) / total);

    context.beginPath();
    context.strokeStyle = color;
    context.lineWidth   = ARC_WIDTH;
    context.arc(16, 16, 16 - ARC_WIDTH / 2, arcStart, arcEnd);
    context.stroke();
  }

  /** Updates the document's favicon w/ a summary of current stats. */
  Title.prototype.updateFavicon = function updateFavicon() {
    var canvas = document.createElement('canvas');
    canvas.height = canvas.width = 32;
    var context = canvas.getContext('2d');

    var passing = this.stats.passes;
    var pending = this.stats.pending;
    var failing = this.stats.failures;
    var total   = Math.max(this.runner.total, passing + pending + failing);
    drawFaviconArc(context, total, 0,                 passing, '#0e9c57');
    drawFaviconArc(context, total, passing,           pending, '#f3b300');
    drawFaviconArc(context, total, pending + passing, failing, '#ff5621');

    this.setFavicon(canvas.toDataURL());
  };

  /** Sets the current favicon by URL. */
  Title.prototype.setFavicon = function setFavicon(url) {
    var current = document.head.querySelector('link[rel="icon"]');
    if (current) {
      document.head.removeChild(current);
    }

    var link = document.createElement('link');
    link.rel = 'icon';
    link.type = 'image/x-icon';
    link.href = url;
    link.setAttribute('sizes', '32x32');
    document.head.appendChild(link);
  };

  var _reporters = {
    get htmlSuites () { return _reporters__htmlSuites; },
    get jsSuites () { return _reporters__jsSuites; },
    get determineReporters () { return determineReporters; },
    get injectMocha () { return injectMocha; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var _reporters__htmlSuites = [];
  var _reporters__jsSuites   = [];

  /**
   * @param {CLISocket} socket The CLI socket, if present.
   * @param {MultiReporter} parent The parent reporter, if present.
   * @return {!Array.<!Mocha.reporters.Base} The reporters that should be used.
   */
  function determineReporters(socket, parent) {
    // Parents are greedy.
    if (parent) {
      return [parent.childReporter(window.location)];
    }

    // Otherwise, we get to run wild without any parental supervision!
    var reporters = [Title, Console];

    if (socket) {
      reporters.push(function(runner) {
        socket.observe(runner);
      });
    }

    if (suites_js.htmlSuites.length > 0 || suites_js.jsSuites.length > 0) {
      reporters.push(HTML);
    }

    return reporters;
  }

  /**
   * Yeah, hideous, but this allows us to be loaded before Mocha, which is handy.
   */
  function injectMocha(Mocha) {
    _injectPrototype(Console, Mocha.reporters.Base.prototype);
    _injectPrototype(HTML,    Mocha.reporters.HTML.prototype);
    // Mocha doesn't expose its `EventEmitter` shim directly, so:
    _injectPrototype(MultiReporter,   Object.getPrototypeOf(Mocha.Runner.prototype));
  }

  function _injectPrototype(klass, prototype) {
    var newPrototype = Object.create(prototype);
    // Only support
    Object.keys(klass.prototype).forEach(function(key) {
      newPrototype[key] = klass.prototype[key];
    });

    klass.prototype = newPrototype;
  }

  var environment_js = {
    get loadSync () { return loadSync; },
    get ensureDependenciesPresent () { return ensureDependenciesPresent; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  function loadSync() {
    util_js.debug('Loading environment scripts:');
    config_js.get('environmentScripts').forEach(function(path) {
      var url = util_js.expandUrl(path, config_js.get('root'));
      util_js.debug('Loading environment script:', url);
      // Synchronous load.
      document.write('<script src="' + encodeURI(url) + '"></script>'); // jshint ignore:line
    });
    util_js.debug('Environment scripts loaded');
  }

  /**
   * We have some hard dependencies on things that should be loaded via
   * `environmentScripts`, so we assert that they're present here; and do any
   * post-facto setup.
   */
  function ensureDependenciesPresent() {
    _ensureMocha();
    _checkChai();
  }

  function _ensureMocha() {
    var Mocha = window.Mocha;
    if (!Mocha) {
      throw new Error('WCT requires Mocha. Please ensure that it is present in WCT.environmentScripts, or that you load it before loading web-component-tester/browser.js');
    }
    _reporters.injectMocha(Mocha);
    // Magic loading of mocha's stylesheet
    var mochaPrefix = util_js.scriptPrefix('mocha.js');
    if (mochaPrefix) { // Not the end of the world, if not.
      util_js.loadStyle(mochaPrefix + 'mocha.css');
    }
  }

  function _checkChai() {
    if (!window.chai) {
      util_js.debug('Chai not present; not registering shorthands');
      return;
    }

    window.assert = window.chai.assert;
    window.expect = window.chai.expect;
  }

  var errors_js = {
    get globalErrors () { return globalErrors; },
    get listenForErrors () { return listenForErrors; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var globalErrors = [];

  /**
   * Hook the environment to pick up on global errors.
   */
  function listenForErrors() {
    window.addEventListener('error', function(event) {
      globalErrors.push(event.error);
    });

    // Also, we treat `console.error` as a test failure. Unless you prefer not.
    var origConsole = console;
    var origError   = console.error;
    console.error = function wctShimmedError() {
      origError.apply(origConsole, arguments);
      if (config_js.get('trackConsoleError')) {
        throw 'console.error: ' + Array.prototype.join.call(arguments, ' ');
      }
    };
  }

  var _mocha = {
    get stubInterfaces () { return stubInterfaces; }
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var MOCHA_EXPORTS = {
    // https://github.com/visionmedia/mocha/blob/master/lib/interfaces/tdd.js
    tdd: {
      'setup':         '"before"',
      'teardown':      '"after"',
      'suiteSetup':    '"beforeEach"',
      'suiteTeardown': '"afterEach"',
      'suite':         '"describe" or "context"',
      'test':          '"it" or "specify"',
    },
    // https://github.com/visionmedia/mocha/blob/master/lib/interfaces/bdd.js
    bdd: {
      'before':     '"setup"',
      'after':      '"teardown"',
      'beforeEach': '"suiteSetup"',
      'afterEach':  '"suiteTeardown"',
      'describe':   '"suite"',
      'context':    '"suite"',
      'xdescribe':  '"suite.skip"',
      'xcontext':   '"suite.skip"',
      'it':         '"test"',
      'xit':        '"test.skip"',
      'specify':    '"test"',
      'xspecify':   '"test.skip"',
    },
  };

  /**
   * Exposes all Mocha methods up front, configuring and running mocha
   * automatically when you call them.
   *
   * The assumption is that it is a one-off (sub-)suite of tests being run.
   */
  function stubInterfaces() {
    Object.keys(MOCHA_EXPORTS).forEach(function(ui) {
      Object.keys(MOCHA_EXPORTS[ui]).forEach(function(key) {
        window[key] = function wrappedMochaFunction() {
          _setupMocha(ui, key, MOCHA_EXPORTS[ui][key]);
          if (!window[key] || window[key] === wrappedMochaFunction) {
            throw new Error('Expected mocha.setup to define ' + key);
          }
          window[key].apply(window, arguments);
        };
      });
    });
  }

  // Whether we've called `mocha.setup`
  var _mochaIsSetup = false;

  /**
   * @param {string} ui Sets up mocha to run `ui`-style tests.
   * @param {string} key The method called that triggered this.
   * @param {string} alternate The matching method in the opposite interface.
   */
  function _setupMocha(ui, key, alternate) {
    var mochaOptions = config_js.get('mochaOptions');
    if (mochaOptions.ui && mochaOptions.ui !== ui) {
      var message = 'Mixing ' + mochaOptions.ui + ' and ' + ui + ' Mocha styles is not supported. ' +
                    'You called "' + key + '". Did you mean ' + alternate + '?';
      throw new Error(message);
    }
    if (_mochaIsSetup) return;
    mochaOptions.ui = ui;
    mocha.setup(mochaOptions);  // Note that the reporter is configured in run.js.
  }

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  var SOCKETIO_ENDPOINT = window.location.protocol + '//' + window.location.host;
  var SOCKETIO_LIBRARY  = SOCKETIO_ENDPOINT + '/socket.io/socket.io.js';

  /**
   * A socket for communication between the CLI and browser runners.
   *
   * @param {string} browserId An ID generated by the CLI runner.
   * @param {!io.Socket} socket The socket.io `Socket` to communicate over.
   */
  function CLISocket(browserId, socket) {
    this.browserId = browserId;
    this.socket    = socket;
  }

  /**
   * @param {!Mocha.Runner} runner The Mocha `Runner` to observe, reporting
   *     interesting events back to the CLI runner.
   */
  CLISocket.prototype.observe = function observe(runner) {
    this.emitEvent('browser-start', {
      url: window.location.toString(),
    });

    // We only emit a subset of events that we care about, and follow a more
    // general event format that is hopefully applicable to test runners beyond
    // mocha.
    //
    // For all possible mocha events, see:
    // https://github.com/visionmedia/mocha/blob/master/lib/runner.js#L36
    runner.on('test', function(test) {
      this.emitEvent('test-start', {test: getTitles(test)});
    }.bind(this));

    runner.on('test end', function(test) {
      this.emitEvent('test-end', {
        state:    getState(test),
        test:     getTitles(test),
        duration: test.duration,
        error:    test.err,
      });
    }.bind(this));

    runner.on('childRunner start', function(childRunner) {
      this.emitEvent('sub-suite-start', childRunner.share);
    }.bind(this));

    runner.on('childRunner end', function(childRunner) {
      this.emitEvent('sub-suite-end', childRunner.share);
    }.bind(this));

    runner.on('end', function() {
      this.emitEvent('browser-end');
    }.bind(this));
  };

  /**
   * @param {string} event The name of the event to fire.
   * @param {*} data Additional data to pass with the event.
   */
  CLISocket.prototype.emitEvent = function emitEvent(event, data) {
    this.socket.emit('client-event', {
      browserId: this.browserId,
      event:     event,
      data:      data,
    });
  };

  /**
   * Builds a `CLISocket` if we are within a CLI-run environment; short-circuits
   * otherwise.
   *
   * @param {function(*, CLISocket)} done Node-style callback.
   */
  CLISocket.init = function init(done) {
    var browserId = util_js.getParam('cli_browser_id');
    if (!browserId) return done();
    // Only fire up the socket for root runners.
    if (ChildRunner.current()) return done();

    util_js.loadScript(SOCKETIO_LIBRARY, function(error) {
      if (error) return done(error);

      var socket = io(SOCKETIO_ENDPOINT);
      socket.on('error', function(error) {
        socket.off();
        done(error);
      });

      socket.on('connect', function() {
        socket.off();
        done(null, new CLISocket(browserId, socket));
      });
    });
  };

  // Misc Utility

  /**
   * @param {!Mocha.Runnable} runnable The test or suite to extract titles from.
   * @return {!Array.<string>} The titles of the runnable and its parents.
   */
  function getTitles(runnable) {
    var titles = [];
    while (runnable && !runnable.root && runnable.title) {
      titles.unshift(runnable.title);
      runnable = runnable.parent;
    }
    return titles;
  }

  /**
   * @param {!Mocha.Runnable} runnable
   * @return {string}
   */
  function getState(runnable) {
    if (runnable.state === 'passed') {
      return 'passing';
    } else if (runnable.state == 'failed') {
      return 'failing';
    } else if (runnable.pending) {
      return 'pending';
    } else {
      return 'unknown';
    }
  }

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */

  // Make sure that we use native timers, in case they're being stubbed out.
  var setInterval           = window.setInterval;           // jshint ignore:line
  var helpers_js__setTimeout            = window.setTimeout;            // jshint ignore:line
  var requestAnimationFrame = window.requestAnimationFrame; // jshint ignore:line

  /**
   * Runs `stepFn`, catching any error and passing it to `callback` (Node-style).
   * Otherwise, calls `callback` with no arguments on success.
   *
   * @param {function()} callback
   * @param {function()} stepFn
   */
  window.safeStep = function safeStep(callback, stepFn) {
    var err;
    try {
      stepFn();
    } catch (error) {
      err = error;
    }
    callback(err);
  };

  /**
   * Runs your test at declaration time (before Mocha has begun tests). Handy for
   * when you need to test document initialization.
   *
   * Be aware that any errors thrown asynchronously cannot be tied to your test.
   * You may want to catch them and pass them to the done event, instead. See
   * `safeStep`.
   *
   * @param {string} name The name of the test.
   * @param {function(?function())} testFn The test function. If an argument is
   *     accepted, the test will be treated as async, just like Mocha tests.
   */
  window.testImmediate = function testImmediate(name, testFn) {
    if (testFn.length > 0) {
      return testImmediateAsync(name, testFn);
    }

    var err;
    try {
      testFn();
    } catch (error) {
      err = error;
    }

    test(name, function(done) {
      done(err);
    });
  };

  /**
   * An async-only variant of `testImmediate`.
   *
   * @param {string} name
   * @param {function(?function())} testFn
   */
  window.testImmediateAsync = function testImmediateAsync(name, testFn) {
    var testComplete = false;
    var err;

    test(name, function(done) {
      var intervalId = setInterval(function() {
        if (!testComplete) return;
        clearInterval(intervalId);
        done(err);
      }, 10);
    });

    try {
      testFn(function(error) {
        if (error) err = error;
        testComplete = true;
      });
    } catch (error) {
      err = error;
      testComplete = true;
    }
  };

  /**
   * Triggers a flush of any pending events, observations, etc and calls you back
   * after they have been processed.
   *
   * @param {function()} callback
   */
  window.flush = function flush(callback) {
    // Ideally, this function would be a call to Polymer.flush, but that doesn't
    // support a callback yet (https://github.com/Polymer/polymer-dev/issues/115),
    // ...and there's cross-browser flakiness to deal with.

    // Make sure that we're invoking the callback with no arguments so that the
    // caller can pass Mocha callbacks, etc.
    var done = function done() { callback(); };

    // Because endOfMicrotask is flaky for IE, we perform microtask checkpoints
    // ourselves (https://github.com/Polymer/polymer-dev/issues/114):
    var isIE = navigator.appName == 'Microsoft Internet Explorer';
    if (isIE && window.Platform && window.Platform.performMicrotaskCheckpoint) {
      var reallyDone = done;
      done = function doneIE() {
        Platform.performMicrotaskCheckpoint();
        helpers_js__setTimeout(reallyDone, 0);
      };
    }

    // Everyone else gets a regular flush.
    var scope = window.Polymer || window.WebComponents;
    if (scope && scope.flush) {
      scope.flush();
    }

    // Ensure that we are creating a new _task_ to allow all active microtasks to
    // finish (the code you're testing may be using endOfMicrotask, too).
    helpers_js__setTimeout(done, 0);
  };

  /**
   * Advances a single animation frame.
   *
   * Calls `flush`, `requestAnimationFrame`, `flush`, and `callback` sequentially
   * @param {function()} callback
   */
  window.animationFrameFlush = function animationFrameFlush(callback) {
    flush(function() {
      requestAnimationFrame(function() {
        flush(callback);
      });
    });
  };

  /**
   * DEPRECATED: Use `flush`.
   * @param {function} callback
   */
  window.asyncPlatformFlush = function asyncPlatformFlush(callback) {
    console.warn('asyncPlatformFlush is deprecated in favor of the more terse flush()');
    return window.flush(callback);
  };

  /**
   *
   */
  window.waitFor = function waitFor(fn, next, intervalOrMutationEl, timeout, timeoutTime) {
    timeoutTime = timeoutTime || Date.now() + (timeout || 1000);
    intervalOrMutationEl = intervalOrMutationEl || 32;
    try {
      fn();
    } catch (e) {
      if (Date.now() > timeoutTime) {
        throw e;
      } else {
        if (isNaN(intervalOrMutationEl)) {
          intervalOrMutationEl.onMutation(intervalOrMutationEl, function() {
            waitFor(fn, next, intervalOrMutationEl, timeout, timeoutTime);
          });
        } else {
          helpers_js__setTimeout(function() {
            waitFor(fn, next, intervalOrMutationEl, timeout, timeoutTime);
          }, intervalOrMutationEl);
        }
        return;
      }
    }
    next();
  };

  /**
   * Runs the Chrome Accessibility Developer Tools Audit against a test-fixture
   *
   * @param {String} fixtureId ID of the fixture element in the document to use
   */
  window.a11ySuite = function a11ySuite(fixtureId) {

    // capture a reference to the fixture element early
    var fixtureElement = document.getElementById(fixtureId);

    // build a mocha suite
    suite('A11y Audit', function() {

      // keep an easy reference to the a11y audit results
      var auditResults;
      function getResult(index) {
        return auditResults[index];
      }

      // build an audit config to disable certain ignorable tests
      var axsConfig = new axs.AuditConfiguration();
      axsConfig.scope = document.body;
      axsConfig.showUnsupportedRulesWarning = false;

      // filter out rules that only run in the extension
      var rules = axs.AuditRules.getRules().filter(function(rule) {
        return !rule.requiresConsoleAPI;
      });

      rules.forEach(function(rule, index) {
        test(rule.heading, function() {
          var result = getResult(index);
          if (result.result === 'FAIL') {
            var message = axs.Audit.accessibilityErrorMessage(result);
            assert.fail(null, null, message);
          }
        });
      });

      // setup fixture and run audit
      suiteSetup(function() {
        assert.ok(fixtureElement, 'fixtureElement should be defined');
        fixtureElement.create();
        auditResults = axs.Audit.run(axsConfig);
      });

      // teardown fixture
      suiteTeardown(function() {
        fixtureElement.restore();
      });
    });
  };

  /**
   * @license
   * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
   * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
   * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
   * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
   * Code distributed by Google as part of the polymer project is also
   * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
   */
  /**
   * This file is the entry point into `web-component-tester`'s browser client.
   */
  config_js.setup(window.WCT);

  // Maybe some day we'll expose WCT as a module to whatever module registry you
  // are using (aka the UMD approach), or as an es6 module.
  var WCT = window.WCT = {};
  // A generic place to hang data about the current suite. This object is reported
  // back via the `sub-suite-start` and `sub-suite-end` events.
  WCT.share = {};
  // Until then, we get to rely on it to expose parent runners to their children.
  WCT._ChildRunner = ChildRunner;
  WCT._config      = config_js._config;


  // Public Interface

  /**
   * Loads suites of tests, supporting both `.js` and `.html` files.
   *
   * @param {!Array.<string>} files The files to load.
   */
  WCT.loadSuites = suites_js.loadSuites;


  // Load Process

  errors_js.listenForErrors();
  _mocha.stubInterfaces();
  environment_js.loadSync();

  // Give any scripts on the page a chance to declare tests and muck with things.
  document.addEventListener('DOMContentLoaded', function() {
    util_js.debug('DOMContentLoaded');

    environment_js.ensureDependenciesPresent();

    // We need the socket built prior to building its reporter.
    CLISocket.init(function(error, socket) {
      if (error) throw error;

      // Are we a child of another run?
      var current = ChildRunner.current();
      var parent  = current && current.parentScope.WCT._reporter;
      util_js.debug('parentReporter:', parent);

      var childSuites    = suites_js.activeChildSuites();
      var reportersToUse = _reporters.determineReporters(socket, parent);
      // +1 for any local tests.
      var reporter = new MultiReporter(childSuites.length + 1, reportersToUse, parent);
      WCT._reporter = reporter; // For environment/compatibility.js

      // We need the reporter so that we can report errors during load.
      suites_js.loadJsSuites(reporter, function(error) {
        // Let our parent know that we're about to start the tests.
        if (current) current.ready(error);
        if (error) throw error;

        // Emit any errors we've encountered up til now
        errors_js.globalErrors.forEach(function onError(error) {
          reporter.emitOutOfBandTest('Test Suite Initialization', error);
        });

        suites_js.runSuites(reporter, childSuites, function(error) {
          // Make sure to let our parent know that we're done.
          if (current) current.done();
          if (error) throw error;
        });
      });
    });
  });

})();
//# sourceMappingURL=./browser.js.map