Karma/Istanbul Code Coverage does not find functions and always returns 100%
<p>I am attempting to add Code Coverage for my Karma tests, however although it finds the correct JS files that I'm testing, it does not find the functions inside those files.</p>

<p>From what I have read so far I believe it to be to do with the files not being correctly browserified before being passed to istanbul to do the coverage, but admittedly I am new to this so I'm hoping for some suggestions.</p>

<p>Here is my JS file(common.js):</p>

<pre><code>var applicationSettings = require('./settings');

var common = {
    getAjaxBaseUrl: function () {
        var strVirtualDirectory = applicationSettings.VirtualDirectory;
        if (strVirtualDirectory.length &gt; 1) {
            if (!strVirtualDirectory.startsWith("/")) {
                strVirtualDirectory = "/" + strVirtualDirectory;
            }
        }
    return strVirtualDirectory;
   }
}
module.exports = common;
</code></pre>

<p>And here are the tests I have written:</p>

<pre><code>it('Client - Should get correct AjaxBaseUrl with /', function () {
    var clientSettings = require('./../client/scripts/settings');
    var clientCommon = require('./../client/scripts/common');

    clientSettings.VirtualDirectory = '/VD';
    expect(clientCommon.getAjaxBaseUrl()).to.equal('/VD');

});

it('Client - Should get correct AjaxBaseUrl without /', function () {
    var clientSettings = require('./../client/scripts/settings');
    var clientCommon = require('./../client/scripts/common');

    clientSettings.VirtualDirectory = 'VD';
    expect(clientCommon.getAjaxBaseUrl()).to.equal('/VD');
});
</code></pre>

<p>My Karma.conf is below:</p>

<pre><code>// Karma configuration
// Generated on Mon Jan 11 2016 09:43:00 GMT+0000 (GMT Standard Time)

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

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

        // frameworks to use
        // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
        frameworks: ['phantomjs-shim', 'browserify', 'mocha'],

        // list of files / patterns to load in the browser
        files: [
            'https://code.jquery.com/jquery-2.2.0.min.js',
            'http://cdn.kendostatic.com/2015.3.1111/js/kendo.all.min.js',
            'test_unit/*Spec.js',
            'client/scripts/*.js'
        ],

        // 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_unit/*Spec.js': ['browserify'],
            'client/scripts/*.js': ['browserify', 'coverage']    
        },

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

        // Configure jUnit reporter
        junitReporter: {
            outputDir: '', // results will be saved as $outputDir/$browserName.xml 
            outputFile: undefined, // if included, results will be saved as $outputDir/$browserName/$outputFile 
            suite: '', // suite will become the package name attribute in xml testsuite element 
            useBrowserName: true // add browser name to report and classes names 
        },

        // Configure coverage reporter
        coverageReporter: {
            type: 'html',
            dir: 'test_coverage',
            subdir: '.',
            file: 'coverage.htm'
        },

        // 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: false,

        browserify: {
            configure: function (bundle) {
                bundle.transform('reactify', { extensions: ['.jsx'] });
            }        
        },        

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

        // Concurrency level
        // how many browser should be started simultaneous
        concurrency: Infinity,

    })
}
</code></pre>

<p>This does produce a report, but this shows 100% and the only line found in the common.js file is:</p>

<pre><code>require("C:\\Source\\ProjectName\\client\\scripts\\common.js");
</code></pre>

<p>I attempted to add Browerify-Istanbul into the mix, by adding a require for it at the top of the Karma.conf an additional transform in the browserify section</p>

<pre><code>bundle.transform(istanbul)
</code></pre>

<p>However this just makes my tests fail and throw several errors:</p>

<blockquote>
  <p>undefined is not an object (evaluating
  '__cov_qQLFhXEMt7fatxiMx0_vQQ.b[' 1'][0]')
  getAjaxBaseUrl@C:/Users/CHARLE~1.WIC/AppData/Local/Temp/0d61da722d2838c9
  600d83d1cbb4c0b8.browserify:43:1498
  C:/Users/CHARLE~1.WIC/AppData/Local/Temp/0d61da722d2838c9600d83d1cbb4c0b
  8.browserify:51742:1849</p>
  
  <p>16 02 2016 09:14:08.515:ERROR [coverage]: [TypeError: Cannot read
  property 'star t' of undefined] TypeError: Cannot read property
  'start' of undefined
      at C:\Source\ProjectName\node_modules\istanbul\lib\o bject-utils.js:59:44
      at Array.forEach (native)
      at Object.addDerivedInfoForFile (C:\Source\ProjectName\node_modules\istanbul\lib\object-utils.js:58:37)
      at Object.Collector.fileCoverageFor (C:\Source\ProjectName\node_modules\istanbul\lib\collector.js:94:15)
      at C:\Source\ProjectName\node_modules\istanbul\lib\r eport\html.js:558:90
      at Array.forEach (native)
      at HtmlReport.Report.mix.writeReport (C:\Source\ProjectName\node_modules\istanbul\lib\report\html.js:557:27)
      at writeReport (C:\Source\ProjectName\node_modules\k arma-coverage\lib\reporter.js:62:16)
      at C:\Source\ProjectName\node_modules\karma-coverage \lib\reporter.js:288:11
      at C:\Source\ProjectName\node_modules\karma\lib\help er.js:82:7
      at FSReqWrap.oncomplete (fs.js:82:15)</p>
</blockquote>

<p>Am I missing something, or going about this the wrong way?</p>