Karma + RequireJS: Mismatched anonymous define error

gulpfile.js

var gulp = require('gulp');

// Plugins
var karma = require('gulp-karma');

// Paths
var basePath = './public/assets/';
var paths = {
  spec: basePath + 'spec/'
};

/**
 * Compile SASS down to CSS using compass
 */
function compileCSS() {
  var stream = gulp.src(paths.sass + '*.sass')
    .pipe(compass({
        css: paths.css,
        sass: paths.sass,
        image: paths.images,
        style: 'nested'
    }))
    .on('error', console.log)
    .pipe(gulp.dest(paths.css));
  return stream;
}

/**
 * Test through Karma
 */
var test = {
  // Watch specs for changes and run tests on change
  watch: function() {
    gulp.watch(paths.spec + '**/*.coffee', ['test-compile']);
    return test.go('watch');
  },
  // Run the tests once
  run: function() {
    test.compile();
    test.go('run');
  },
  // Test run/watch helper: either runs or launches a single test
  go: function(action) {
    var files = ["undefined.js"];
    return gulp.src(files)
      .pipe(karma({
        configFile: 'karma.conf.js',
        action: action
      }));
  }
};

gulp.task('test', test.run);
gulp.task('test-run', test.run);
gulp.task('test-watch', test.watch);

karma.conf.js

module.exports = function(config) {
  config.set({
    // base path, that will be used to resolve files and exclude
    basePath: 'public',

    // frameworks to use
    frameworks: ['jasmine', 'requirejs'],

    // list of files / patterns to load in the browser
    files: [
      {pattern: 'assets/js/app/**/*.js', included: false},
      {pattern: 'assets/js/libs/**/*.js', included: false},
      {pattern: 'assets/spec/*Spec.js', included: false},
      'assets/js/app/config.js',
      'assets/spec/test-config.js'
    ],

    // test results reporter to use
    // possible values: 'dots', 'progress', 'junit', 'growl', 'coverage'
    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, currently available:
    // - Chrome
    // - ChromeCanary
    // - Firefox
    // - Opera (has to be installed with `npm install karma-opera-launcher`)
    // - Safari (only Mac; has to be installed with `npm install karma-safari-launcher`)
    // - PhantomJS
    // - IE (only Windows; has to be installed with `npm install karma-ie-launcher`)
    browsers: ['PhantomJS'],

    // If browser does not capture in given timeout [ms], kill it
    captureTimeout: 60000,

    // Continuous Integration mode
    // if true, it capture browsers, run tests and exit
    singleRun: false
  });
};