$(document).ready(function(jQuery) { // a mock object that looks sufficiently jQuery-ish var myLib = function() { return { attr: function() { return "spam" }, html: function() { return "spam" }, hasClass: function() { return "spam" } }; }; var viewAttrs = { id: 'test-setdomlibrary', className: 'test-setdomlibrary' } module("Backbone.setDomLibrary", { teardown: function() { Backbone.setDomLibrary(jQuery); } }); test('Changing jQuery library to custom library', function() { Backbone.setDomLibrary(myLib); var view = new Backbone.View(viewAttrs); ok(view.$el.hasClass('test-setdomlibrary') === 'spam'); Backbone.setDomLibrary(jQuery); var view = new Backbone.View(viewAttrs); ok(view.$el.hasClass('test-setdomlibrary')); }); });