Why is Karma not receiving a message from the browser after tests execution completes?

Question

A test was failing with:

Error: timeout of 2000ms exceeded. Ensure the done() callback is being called in this test.

So I added this.timeout(0) to it, then I got:

Disconnected, because no message in 10000 ms.

I went on to add browserNoActivityTimeout: 0 to my config file.

When I try to run the tests, the browser opens and the console shows the passed test.

SUCCESS

Skipped 0 tests

Why is the browser not being closed? What is it waiting for?

browserNoActivityTimeout

How long will Karma wait for a message from a browser before disconnecting from it (in ms).

https://github.com/karma-runner/karma/blob/master/docs/config/01-configuration-file.md#browsernoactivitytimeout

Command:

karma start --single-run

Config:

webpackConfig.module.loaders.push({
  test: /\.js$/,
  include: /src/,
  exclude: /node_modules/,
  loader: 'isparta'
});

var karmaConfig = {
  frameworks: ['mocha'],
  browsers: ['Chrome'],
  //browserNoActivityTimeout: 0,
  logLevel: 'INFO',
  //reporters: ['progress', 'coverage-allsources', 'coverage'],
  reporters: ['progress', 'coverage'],
  autoWatch: true,
  files: [
    'test/karma.js'
  ],
  urlRoot: '/karma-runner/',
  preprocessors: {
    'test/karma.js': ['webpack', 'sourcemap']
  },
  webpackMiddleware: {
    stats: 'minimal',
    watchOptions: {
      aggregateTimeout: 300
    }
  },
  webpack: webpackConfig,
  coverageReporter: {
    dir: 'report/coverage',
    include: 'src/**/*.js',
    // Any .js files that are not imported/required need to be added to the 
    // exclude:, otherwise you will get a JS error for
    // 'Unexpected token in esprima.js'.
    // This appears to be a bug with the karma-coverage-allsources repo.
    exclude: 'src/init.js',
    reporters: [
      {'type' : 'cobertura'},
      {'type' : 'html'},
      {'type': 'text-summary'}
    ]
  }
};

Answer 1

Five minutes after typing the question, I find the answer.

The entry point "test/karma.js" has code that opens the debug tab and that is probably interrupting somehow Karma.

window.open('/karma-runner/debug.html', '_blank');