title: How to setup Karma runner code coverage?
body: <p>I am attempting to get Karma runner to generate cobertura formatted code coverage reports during a Jenkins build.  I can get it to generate a coverage.xml file, but it does not actually have any coverage data.  It appears (using <code>LOG_DEBUG</code>) that the coverage preprocessor is not running.</p>
  
  <p>The relevant pieces from my <code>karma.conf.js</code> file are:</p>
  
  <pre><code>files = [
    JASMINE,
    JASMINE_ADAPTER,
    'app/components/angular/angular.js',
    'app/components/angular-mocks/angular-mocks.js',
    'tmp/scripts/**/*.js',
    'tmp/spec/**/*.js'
  ];
  
  preprocessors = {
    'tmp/scripts/**/*.js': 'coverage'
  };
  
  // test results reporter to use
  // possible values: 'dots', 'progress', 'junit'
  reporters = ['dots', 'junit', 'coverage'];
  
  junitReporter = {
    outputFile: 'test-results.xml'
  };
  
  coverageReporter = {
    type: 'cobertura',
    dir: 'coverage/',
    file: 'coverage.xml'
  };
  </code></pre>
  
  <p>(The junit report is generating fine.)</p>