Erreur Karma

Bonjour,

Voila je rencontre un petit problème avec mon code. j'essaye de mettre en place les test unitaires dans mon projet.pour cela j'utilise Karma et jasmine.
Ma page karma.config.js

// Karma configuration
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: ['jasmine'],

    // list of files / patterns to load in the browser
    files: [
      'public/javascripts/lib/angular.min.js',
      //'public/javascripts/lib/*.js',
      'node_modules/angular-mocks/angular-mocks.js',
      'app.js',
      'tests/test1/test1.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 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,

    // Concurrency level
    // how many browser should be started simultaneous
    concurrency: Infinity,
     plugins : [
        'karma-chrome-launcher',
        'karma-jasmine'

    ]
  })
}

Lorsque je démarre Karma le serveur démarre mais ensuite j'ai une erreur de type

Chrome 54.0.2840 (Windows 7 0.0.0) ERROR
  Uncaught ReferenceError: require is not defined
  at app.js:1

quelqu'un aurait il une idée sur la source du probléme.
Merci :)