code: function _browserifyBundle() {
      let bundler = browserifyBundler();
      // Watch the bundler, and re-bundle it whenever files change
      bundler = watchify(bundler);
      bundler.on('update', () => _runBrowserifyBundle(bundler));
  
      return _runBrowserifyBundle(bundler);
  }
docs: Build the unit test suite for running tests in the browser