bootstrap/js/tests/unit/affix.js

$(function () {

    module('affix')

      test('should provide no conflict', function () {
        var affix = $.fn.affix.noConflict()
        ok(!$.fn.affix, 'affix was set back to undefined (org value)')
        $.fn.affix = affix
      })

      test('should be defined on jquery object', function () {
        ok($(document.body).affix, 'affix method is defined')
      })

      test('should return element', function () {
        ok($(document.body).affix()[0] == document.body, 'document.body returned')
      })

      test('should exit early if element is not visible', function () {
        var $affix = $('<div style="display: none"></div>').affix()
        $affix.data('bs.affix').checkPosition()
        ok(!$affix.hasClass('affix'), 'affix class was not added')
      })

})