You *can* have nested describes in Jasmine.

gistfile1.js

describe('util.Config', function() {
  describe('.openerType', function() {
    var Config, Device;

    beforeEach(function() {
      Device = {};
      Config = theBestDay.require('widget.Config', {'util.Device': Device});
    });

    describe('desktop', function() {
      beforeEach(function() {
        Device.isMobile = function() { return false; };
      });

      it('defaults to config', function() {
        var url = Config.childUrl();

        expect(url).toBe('<%= site.config["child"]["desktop_url"] %>');
      });

      it('is given child URL', function() {
        var url = Config.childUrl({mobile: '/mobile', desktop: '/desktop'});

        expect(url).toBe('/desktop');
      });
    });
  });
});