Javascript karma getElementById空错误

在我的javascript中，document.getElementById总是返回null，以防因果报应。当我直接在浏览器上加载html时，这没有问题。我认为因果报应的配置是错误的

// Karma configuration
// Generated on Sun Jul 26 2015 14:08:25 GMT+0900 (JST)

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: ['mocha'],


// list of files / patterns to load in the browser
files: [
  'listtest.html',
  {pattern: 'js/*.js', included: false},
  {pattern: 'test/*.js', included: false}
],


// 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
  })
}

---

我的错误是什么？

我发现karma不能默认包含html文件。要加载html，必须使用html2js预处理器。在将html转换为js后，karma可以将html分配给document对象，但我不知道如何做